INDUSTRIAL     CHEMISTRY 


BEING    A    S  E  R  r  R  S    OF    VOLUMES    G  1  V  I N 
A    COMPREHENSIVE     SURVEY     OF 

THE    CHEMICAL    INDUSTRIES 


INDUSTRIAL    CHEMISTRY 

BEING   A   SERIES   OF  VOLUMES   GIVING   A 
COMPREHENSIVE   SURVEY   OF 

THE    CHEMICAL    INDUSTRIES 

EDITED  BY  SAMUEL  RIDEAL,  D.Sc.  LOND.,  F.I.C. 

FELLOW  OF   UNIVERSITY  COLLEGE,   LONDON 

ASSISTED   BY 

JAMES  A.  AUDLEY,  B.Sc.  J.  R.  PARTINGTON,  D.Sc.  (Viet.) 

W.  BACON,  B.Sc.,  F.I.C.  ARTHUR  E.  PRATT,  B.Sc. 

M.  BARROWCLIFF,  F.I.C.  ERIC  K.  RIDEAL,  PH.D.,  M.A.,  F.I.C. 

H.  GARNER  BENNETT,  M.Sc.  W.  H.  SIMMONS,  B.Sc. 

F.  H.  CARR,  F.I.C.  R.  W.  SINDALL,  F.C.S. 

S.  HOARE  COLLINS,  M.Sc.,  F.I.C.  SAMUEL  SMILES,  D.Sc. 

H.  H.  GRAY,  B.Sc.  D.  A.  SUTHERLAND,  F.C.S. 

H.  C.  GREENWOOD,  D.Sc.  HUGH  S.  TAYLOR,  D.Sc. 
C.  M.  WHITTAKER,  B.Sc. 


First  Edition     .     .     April >  1918 
Reprinted     .     .     .     January,  1919 


PLANT    PRODUCTS   AND 
CHEMICAL  FERTILIZERS 


BY 

S.    HOARE    COLLINS,    M.Sc.,  F.I.C. 

LECTURER    AND    ADVISER    IN    AGRICULTURAL   CHEMISTRY,    ARMSTRONG 
COLLEGE,    NEWCASTLE-ON-TYNE    (UNIVERSITY   OF   DURHAM)  ; 
FORMERLY   ASSISTANT    AGRICULTURAL   CHEMIST   TO   THE 
GOVERNMENT   OF   INDIA  ;   AUTHOR   OF   "  HAND- 
BOOK   OF   AGRICULTURAL   CHEMISTRY 
FOR   INDIAN   STUDENTS  " 


NEW  YORK 
D.    VAN    NOSTRAND    COMPANY 

25   PARK    PLACE 
1919 


PRINTED  IN   GREAT   BRITAIN 


GENERAL   PREFACE 

THE  rapid  development  of  Applied  Chemistry  in  recent  years 
has  brought  about  a  revolution  in  all  branches  of  technology. 
This  growth  has  been  accelerated  during  the  war,  and  the 
British  Empire  has  now  an  opportunity  of  increasing  its 
industrial  output  by  the  application  of  this  knowledge  to  the 
raw  materials  available  in  the  different  parts  of  the  world. 
The  subject  in  this  series  of  handbooks  will  be  treated  from 
the  chemical  rather  than  the  engineering  standpoint.  The 
industrial  aspect  will  also  be  more  prominent  than  that  of 
the  laboratory.  Each  volume  will  be  complete  in  itself,  and 
will  give  a  general  survey  of  the  industry,  showing  how 
chemical  principles  have  been  applied  and  have  affected 
manufacture.  The  influence  of  new  inventions  on  the 
development  of  the  industry  will  be  shown,  as  also  the 
effect  of  industrial  requirements  in  stimulating  invention. 
Historical  notes  will  be  a  feature  in  dealing  with  the 
different  branches  of  the  subject,  but  they  will  be  kept 
within  moderate  limits.  Present  tendencies  and  possible 
future  developments  will  have  attention,  and  some  space 
will  be  devoted  to  a  comparison  of  industrial  methods  and 
progress  in  the  chief  producing  countries.  There  will  be  a 
general  bibliography,  and  also  a  select  bibliography  to  follow 
each  section.  Statistical  information  will  only  be  introduced 
in  so  far  as  it  serves  to  illustrate  the  line  of  argument. 

Each  book  will  be  divided  into  sections  instead  of 
chapters,  and  the  sections  will  deal  with  separate  branches 
of  the  subject  in  the  manner  of  a  special  article  or  mono- 
graph. An  attempt  will,  in  fact,  be  made  to  get  away  from 


vi  GENERAL    PREFACE 

the  orthodox  textbook  manner,  not  only  to  make  the  treat- 
ment original,  but  also  to  appeal  to  the  very  large  class  of 
readers  already  possessing  good  textbooks,  of  which  there 
are  quite  sufficient.  The  books  should  also  be  found  useful 
by  men  of  affairs  having  no  special  technical  knowledge,  but 
who  may  require  from  time  to  time  to  refer  to  technical 
matters  in  a  book  of  moderate  compass,  with  references  to 
the  large  standard  works  for  fuller  details  on  special  points 
if  required. 

To  the  advanced  student  the  books  should  be  especially 
valuable.  His  mind  is  often  crammed  with  the  hard  facts 
and  details  of  his  subject  which  crowd  out  the  power  of 
realizing  the  industry  as  a  whole.  These  books  are  intended 
to  remedy  such  a  state  of  affairs.  While  recapitulating  the 
essential  basic  facts,  they  will  aim  at  presenting  the  reality 
of  the  living  industry.  It  has  long  been  a  drawback  of  our 
technical  education  that  the  college  graduate,  on  commencing 
his  industrial  career,  is  positively  handicapped  by  his 
academic  knowledge  because  of  his  lack  of  information  on 
current  industrial  conditions.  A  book  giving  a  compre- 
hensive survey  of  the  industry  can  be  of  .very  material 
assistance  to  the  student  as  an  adjunct  to  his  ordinary  text- 
books, and  this  is  one  of  the  chief  objects  of  the  present 
series.  Those  actually  engaged  in  the  industry  who  have 
specialized  in  rather  narrow  limits  will  probably  find  these 
books  more,  readable  than  the  larger  textbooks  when  they 
wish  to  refresh  their  memories  in  regard  to  branches  of  the 
subject  with  which  they  are  not  immediately  concerned. 

The  volume  will  also  serve  as  a  guide  to  the  standard 
literature  of  the  subject,  and  prove  of  value  to  the  con- 
sultant, so  that,  having  obtained  a  comprehensive  view  of 
the  whole  industry,  he  can  go  at  once  to  the  proper 
authorities  for  more  elaborate  information  on  special  points, 
and  thus  save  a  couple  of  days  spent  in  hunting  through  the 
libraries  of  scientific  societies. 

As  far  as  this  country  is  concerned,  it  is  believed  that 
the  general  scheme  of  this  series  of  handbooks  is  unique, 
and  it  is  confidently  hoped  that  it  will  supply  mental 


GENERAL    PREFACE  vii 

munitions  for  the  coming  industrial  war.  I  have  been 
fortunate  in  securing  writers  for  the  different  volumes  who 
are  specially  connected  with  the  several  departments  of 
Industrial  Chemistry,  and  trust  that  the  whole  series  will 
contribute  to  the  further  development  of  applied  chemistry 
throughout  the  Empire. 

SAMUEL   RIDEAI,. 


PREFACE 

THE  raw  materials  of  Agriculture  are  often  the  waste 
products  of  the  other  industries,  and  the  produce  of  Agri- 
culture again  forms  the  raw  material  for  other  industries. 
The  following  pages  attempt  to  pick  up  the  story  of  those 
industrial  waste  products  which  are  useful  as  fertilizers, 
and  carry  it  on  through  the  soil  and  crops,  until  new 
products  are  available  for  industrial  uses.  Among  the 
many  plant  products  which  are  obtained  from  the  soil,  food 
takes  a  high  position  as  an  industrial  raw  product,  since 
neither  men  nor  horses  could  work  without  it.  No  particular 
effort  is  made  to  give  encyclopaedic  completeness  of  informa- 
tion, but  the  aim  has  been  to  give  a  fair  conspectus  of  a 
large  subject,  with  an  appended  bibliography  for  those 
who  are  able  to  pursue  their  studies  further.  Details  of 
analytical  chemistry  are  not  considered  in  this  volume 
unless  the  standard  text -books  named  in  the  Bibliography 
appear  incomplete  or  unsuitable.  The  volume  covers  the 
cycle  from  factory  to  fertilizer,  from  fertilizer  to  field,  and 
from  field  to  factory  once  more. 

I  have  to  thank  Mr.  A.  S.  Blatchford,  M.Sc.,  for  valuable 
help  in  revising  proof-sheets. 

S.   HOARK   COWJNS. 

February,  1918. 


CONTENTS 


PAGE 

CONTENTS       ,         .        .,',..,         ,         .         .         ,         .         .       xi 

INTRODUCTION 

Brief  view  of  authorities.         .         .         .         .         .         .         .         ,         I 

The  Sun  as  a  source  of  energy.  The  vegetable  leaf  as  an  absorptive 
agent  to  convert  Solar  energy  into  Chemical  energy.  The  soil  as  a 
medium  for  vegetable  growth.  The  chief  factors  determining 

vegetable  growth 3 

Need  for  fertilizers.      Virgin   soils.     Barren  soils.     Exhausted   soils. 

Losses  and  gains  in  Nature.     Losses  and  gains  in  practice    .         .         3 
The  balance  of  life  .........         8 

References 9 


PART   I.— FERTILIZERS. 

SECTION    i.— NITROGEN   GROUP   OF 
FERTILIZERS. 

General  properties         ......         .  10 

(a)  Sulphate  of  Ammonia.     Origin.     Useful  and   impracticable  mixtures. 

Application  to  the  land.  Physical  and  chemical  properties.  Time  to 
apply.  Secondary  effects  on  the  soil.  Effects  on  crops.  Crops  most 
suited  for  sulphate  of  ammonia  .  .  .  .  .  .  .  n 

(b)  Ammonium  Chloride,  Nitrate,  and  Carbonate      .          .          .          .          -17 

(c)  Nitrate  of  Soda.    Origin.    Mixtures.    Application  to  the  land.    Physical 

and  chemical  properties.  Time  to  apply.  Methods  of  application. 
Ultimate  effect  on  the  soil.  Effect  on  the  crop  grown.  Crops  most 
suited  to  nitrate  of  soda  .  .  .  .  .  .  .  .18 

(d)  Nitrate  of  Lime.     History.     Crops  best  suited.     Difficulties  of  applica- 
tion.    Suitable  mixtures  ........       20 

(e)  Nitrate  of  Potash.    History.     Indian  and  Egyptian  methods  of  manu- 

facture.    Local  agricultural  uses.     Nitre  earths.     Nitre  wells.     Manu- 
facturing wastes      ,         .         .         .         .         •         v         •         •         •       21 
(/)  Calcium  Cyanamide.    Nitrolim.     Storage.     Properties.     Difficulties  of 
application  to  soil.     Times  to  apply.     Crops  most  suited.     Secondary 

effects  on  the  soil *  .21 

xi 


xii  CONTENTS 

PAGE 

(g)  Organic  Nitrogen  Manures.  Fish  meal.  Composition.  Types  of  soil 
and  crop  most  suited.  Objections  and  difficulties.  Dried  blood.  Hoofs 
and  horns.  Refuse  oil  cakes.  Industrial  waste  materials  ...  22 

References 24 


SECTION   2.— THE   PHOSPHORUS   GROUP   OF 
FERTILIZERS. 

General  properties.  Chemical  condition.  The  different  phosphorus  com- 
pounds used  as  fertilizers  .  ....  .  .  .  25 

(a)  Basic  Slag.    History  and  development.    Composition.    Citric  solubility. 

Fineness.  Application  to  the  soil.  Soils  most  suited.  Crops  giving 
good  returns.  Factors  needed  to  ensure  success.  Secondary  and 
ultimate  effects  on  the  physical  condition  of  the  soil.  Lasting  effect  .  27 

(b)  Mineral  Phosphates.     Occurrence  and  distribution.     Direct  use  on  the 

land.  Secondary  effects.  Water  solubility.  Citric  solubility.  Solu- 
bility in  other  reagents.  Reversion  ......  30 

(f)  Fertilizers  containing  both  Nitrogen  and  Phosphorus.  Bones.  Bone  meal. 
Bone  flour.  Dissolved  bones.  Guano.  Mixtures  to  imitate  guano  or 
dissolved  bones.  General  considerations  on  time  to  apply  mixed 
nitrogen  and  phosphorus  fertilizers.  Their  relative  value  and  suitability 
on  different  soils  and  to  different  crops  ......  32 

References 36 


SECTION   3.— POTASSIUM   GROUP  OF  MANURES 

German  potash  manures.  Geological  origin.  Kainit.  Muriate  and  sulphate. 
Nitre.  Wood  ashes.  Blast  furnace  dust.  General  reactions  of  potash 
manures  in  the  soil  .  .  .  .  .  .  .  .  37 

References  .  .         «...       39 


SECTION   4.— MIXED    FERTILIZERS. 

(a)  Containing  nitrogen,  phosphorus,  and  potassium.    (Artificial  mixtures)  .       40 

(b)  Farm-yard  manure.     Its  constituents  ;  cow,  pig,  sheep,  and  horse  dung. 

Urine  of  farm   animals.     Litter  used  in   making  manure.     Physical 
properties  of  litter  .         .     ,    •         •         .         •         •         •         .42 

(c)  Nitrogen,  phosphorus,  and  potassium.     Passage  from  food  to  dung-heap. 

Relationship  between  type  of  food  and  type  of  beast  and  sort  of  manure 
produced.     Quantities  made  under  varying  conditions         .         .         •       48 

(d)  Storage  of  manure.     Denitrification.     Drainage.     Preservation.     Effect 

of  farm-yard  manure  on  the  soil.      Valuation  of  farm-yard  manure. 

Its  lasting  effects 5° 

(e)  Human  excreta.     Sewage.     Sewage  farms.     Sewage  sludge          .         .       54 
(/)  Poultry  dung.      Composts.     Vegetable  mould.      Beech  mast.      Peat. 

Humogen.     Seaweed      .         .         .         •         •         •         •         /         -5" 
References  . 58 


CONTENTS  xiii 


PART  II.— SOILS. 
SECTION    i.— SOILS   AND   THEIR   PROPERTIES. 

PAGE 

(a)  Different  kinds  of  soils  and  their  physical  properties    ....  60 

(b)  Relation  of  soil  to  water.     Methods  of  modifying  the  water  capacity  of 

soils 67 

(c)  The  chemical  properties  of  the  different  classes  of  soils          ...  70 

(d)  Useful  and  useless  elements.      Balance  of  fertilizers.     Available  and 

total  plant  food  in  soils   .........  72 

(<?)  Relation  of  soil  to  air.  Biological  condition  of  soils.  Fixation  of 

nitrogen  ...........  So 

(/)  The  relation  of  soil  to  fertilizer 82 

(g)  "  The  law  of  diminishing  returns  "  from  both  its  scientific  and  practical 

aspects 83 

References  ............  84 


SECTION   2.— SPECIAL   SOIL   IMPROVERS. 

(a)  Lime.  Various  forms  of  lime.  Industrial  waste  lime.  Gypsum  and  its 

special  uses.  Reasons  why  plastering  has  gone  out  of  fashion  .  .  86 

(d)  Electricity 89 

(c)  The  partial  sterilization  of  soils.  Application  of  heat.  Germicides.  Gas 
lime.  Naphthalene.  Soil  injuries.  Effect  of  bad  drainage.  Injuries 
due  to  unskilful  cultivation  ........  90 

References  .         .         .         .         .         .         .         .         .         .         .         .92 


SECTION   3.— SOIL   RECLAMATION. 

(a)  Barren  lands.     Causes  of  barrenness 93 

(b)  Dry  lands.     Their  treatment  and  improvement  .....  94 

(c)  Wet  lands.     Their  treatment  and  improvement  •         ....  95 

(d)  Peat.     Its  reclamation  and  improvement    ......  07 

References Ioo 


PART    III.— CROPS. 

SECTION    i.— PHOTOSYNTHESIS. 

The  conversion  of  Solar  energy  into  materials  which  in  their  turn  develop 
Animal  energy.  The  materials  in  the  crops  produced  by  solar  energy. 
Their  relationship  to  the  fertilizers  used.  The  economy  in  solar 
energy  obtained  by  the  proper  use  of  fertilizers  .  .  .  .  .  101 

References  ..........  no 


xiv  CONTENTS 

SECTION  2.— THE  CARBOHYDRATES  PRODUCED 

IN    CROPS. 

PAGE 

(a)  Sugar.     Its  production  in  tropical  and  temperate  climates.     The  manu- 

facture and  purification   of  sugar.       Sugar-cane,   sugar   beet,   dates, 
mangels,  turnips in 

(b)  Starch.     Its  production  and  manufactured  forms.     Wheat,  maize,  rice, 

potatoes,  sago,  tapioca    .         .         .         .         .         .         .         .         •      H7 

(c)  Cellulose.     Fibres,  etc.    The  chief  kinds.     Their  manufacture  and  uses. 

Cotton,  linen,  jute,  hemp,  timber,  paper 124 

(d)  Gums  and  mucilage  .         .          .          .          .          .          .         .          ''31 

References  ............     132 


SECTION    3.— THE   OIL-BEARING   PLANTS. 

(a)  Linseed.     Its  growth  and  use  for  oil  and  cattle  food.     Poisonous  com- 

pounds sometimes  developed  ........     135 

(b)  Cotton.    Its  growth  and  use  for  oil  and  cattle  food.      Different  kinds 

of  products  according  to  climate  and  methods  of  manufacture       .         .137 

(c)  Soya  bean.     Growth  and  methods  of  pressing  for  oil  and  cattle  food      .     138 

(d)  Palm-nuts  and  coconuts.     Their  growth  and  use  for  oil,  butter  substi- 
tutes, and  cattle  foods 139 

(<?)  Earth-nuts.    Rape,  safflower,  sesame,  niger,  mowha     ....     142 

(/)  The  essential  oils 145 

References  ............     145 


SECTION   4.— THE   NITROGEN   COMPOUNDS 
IN   PLANTS. 

(a)  Cereal  proteins "     .         .147 

(b)  Legumen  proteins    .         .         .         .         .         *         *         .         •         -15° 

(c)  Root  crop  proteins 151 

(d)  Oil  seed  proteins     .         .         .         .  151 

(e)  The  alkaloids 152 

References  .........•••     157 


SECTION    5.— MISCELLANEOUS   PLANT 
PRODUCTS. 

(a)  Tea  and  cocoa         •.....<«..  158 

(6)  Coffee 160 

(c)  Tannin                     * 162 

(d)  Rubber 163 

(e)  Indigo 165 

(/)  Fruit 1 66 

References .168 


CONTENTS  xv 

SECTION   6.— PRODUCE  VARIABILITY. 

PAGE 

The  specific  effects  of  the  different  fertilizers  on  the  different  crops  and  parts 
of  the  same  crop.  Accelerated  and  delayed  ripening.  Assisted  root 
development  ...........  169 

Substances  and  conditions  which  prevent  crops  from  obtaining  the  nutriment 

provided  by  the  fertilizers  given  .  .  .  .  .  .  .176 

References 177 


PART   IV.— THE   PRODUCTION   OF   MEAT. 
SECTION    i  —MANURING   FOR   MEAT. 

The  effect  of  fertilizers  on  the  pastures  and  then  on  the  beasts  grazing.  In- 
fluence of  the  fertilizers  used  on  the  amount  of  meat  produced.  The 
animal  as  a  machine  for  converting  the  low-grade  food  into  high-grade 
food.  The  metabolic  changes  taking  place  in  the  animal  body. 
Tryptophane  and  the  purine  bases  .  .  .  .  .  .  .178 

References  ............     182 


SECTION  2.— THE  FOODS  FED  TO  BEASTS. 

(a)  Water  in  foods.     The  water  supply.     Amounts  necessary.     Effects  of 

excess 183 

(£)  The  fat  in  foods.     Origin  of  fat.     Composition  of  fat   .          .          .          .  184 

(c)  The  proteins.     The  amides 185 

(d)  The  carbo-hydrates  :  sugar,  starch,  pectin,  mucilage,  etc.     .          .          .186 

(<?)   The  fibrous  materials  :  cellulose,  lignin,  etc 187 

(/)  Digestion.     Methods  by  which  digestion  has  been  measured  in  fattening 

beasts 188 

References 190 


SECTION  3.— CALORIFIC   VALUE   OF   FOODS. 

The  animal  as  a  heat  engine.  Loss  of  energy  due  to  urea.  Bacteria, 
chewing,  alimentation,  etc.  Different  systems  of  valuing  foods.  Their 
respective  merits  under  different  conditions.  The  relative  values  of 
different  classes  of  stock  as  a  means  of  converting  cattle  food  into  human 
food  .  .  . 191 

References  ............     198 


SECTION   4.— DAIRY   PRODUCTS. 

As  high-grade  products  obtained  from  low-grade  products          .         .         .     199 
References  .  202 


xvi  CONTENTS 

SECTION    5.— FUTURE   DEVELOPMENTS. 

PAGE 

(a)  Increase  of  field  fertility  by  sound  management .....     203 

(b)  Development  of  agriculture  at  home  and  abroad          ....     205 

(c)  Financial  aspect  of  agriculture  .         .          .          .          .          .          .210 

(d)  Labour  difficulties  .         .         .         .         .         .         .         .         .         .214 

(e)  Education 219 

(f)  Economic  production  of  meat  in  Winter   .         .         .         .         ,         .221 
References 222 

GENERAL  BIBLIOGRAPHY 223 

INDEX      .         .         .         ...         .         .         .         .         .      f  .     225 


PLANT    PRODUCTS 


INTRODUCTION 

THE  study  of  the  products  of  plant  life  that  are  useful 
to  man  formed  one  of  the  first  deliberate  actions  of  early 
intelligence.  Ancient  records  of  China,  India,  and  Egypt 
alike  show  that  the  study  of  the  products  of  plants  attracted 
early  attention. 

The  Latin  authors,  Virgil,  Columella,  and  others  who 
wrote  on  Agricultural  subjects,  are  well  known  in  the  schools, 
and  about  two  hundred  years  ago,  Jethro  Tull,  the  inventor 
of  the  first  seed  drill,  wrote  on  nitre,  water,  and  fire 
and  earth,  as  the  origins  of  plant  products.  Humphrey 
Davy,  one  hundred  years  ago,  published  his  Lectures  on 
Agricultural  Chemistry,  and  up  to  thirty  years  ago  many 
of  the  Professors  of  Chemistry  in  the  Universities,  as  a 
means  of  bringing  home  the  truths  of  their  science  to  the 
members  of  their  audience,  drew  more  illustrations  from 
rural  life  than  from  the  urban  industries. 

Turning  now  to  those  who  specialized  in  Agricultural 
Science  in  England  in  recent  years,  we  find  such  well-known 
names  as  L,awes  and  Gilbert,  who  gave  Rothainsted  a  world- 
wide reputation,  and  Augustus  Voelcker,  whose  work  in  the 
Royal  Agricultural  Society  laid  the  foundations  of  many  of 
the  modern  inquiries  into  Agricultural  Science.  Numerous 
investigators  have  followed  in  the  footsteps  of  these  pioneers, 
and  the  following  pages  will  be  found  full  of  references  to 
their  valuable  work  in  building  up  an  exact  science  of 
chemistry  applied  to  economic  problems  of  the  agriculture  of 
to-day. 

The  sun  is  the  source  of  power.     The  effective  utilization 

D.  I 


'  'PROD  UCTS 


of  solar  energy  in  the  production  of  plant  material  lies 
at  the  basis  of  all  Agricultural  Science  and  Practice.  The 
vegetable  leaf  in  the  plant  is  the  prime  mover  which  starts 
a  long  chain  of  chemical  change,  which  begins  with  the  energy 
derived  from  the  sun  and  the  crude  materials  brought 
chiefly  by  the  winds,  and  is  supplemented  by  operations 
and  materials  more  under  human  control. 
For  nearly  all  plant  products  we  require  — 

(1)  The  radiation  from  the  sun. 

(2)  A  supply  of  water. 

(3)  A  supply  of  air. 

(4)  A  supply  of  fertilizers. 

(5)  Correct  conditions  of  heat,  chemical  reaction,  and 
bacterial  development. 

In  areas  which  are  both  tropical  and  continental  the 
sun's  heat  may  be  excessive  for  plant  development,  whilst 
in  polar  regions  the  supply  of  solar  heat  is  deficient  ;  but  the 
major  part  of  the  earth's  surface  receives  enough  heat  for 
ample  plant  life. 

In  certain  districts  the  amount  of  water  may  be  excessive 
and  in  other  districts  the  reverse  may  be  the  case,  but  recent 
study  shows  that  these  difficulties  can  be  minimized  if  not 
overcome.  The  supply  of  air  to  the  leaf  is  usually  sufficient, 
but  the  supply  of  air  to  the  roots  of  a  plant  very  frequently 
needs  careful  management  to  obtain  the  best  result. 

Some  soils  are  fairly  well  supplied  by  nature  with 
appropriate  fertilizers,  but  since  the  requirements  of  man 
are  very  diverse,  it  is  a  virtual  impossibility  for  a  soil  to  be  so 
"  fertile  "  that  it  needs  no  manure  to  produce  the  intensive 
and  varied  crops  which  modern  conditions  may  demand. 

Economic  conditions  may,  however,  prevent  the  produc- 
tion of  a  maximum  crop  under  intensive  cultivation.  It  does 
not  always  pay  to  produce  maximum  crops,  and  hence  some 
lands  are  said  to  be  so  fertile  as  not  to  need  fertilizers.  The 
present  war  is  teaching  us  that  too  much  reliance  may  be 
put  upon  the  economic  aspect  of  food  production  ;  that 
the  interests  of  the  nation  are  not  identical  with  those  of 
the  producer. 


INTRODUCTION  3 

No  soil  is  perfect ;  no  soil  quite  hopeless  ;  much  can  be 
done  to  improve  the  bad,  and  much  can  be  left  undone  to 
injure  the  good.  Those  soils  which  have  grown  grass  or 
timber  for  many  years  have  a  great  accumulated  fertility 
and  need  but  little,  if  any,  fertilizer,  though  it  is  not 
infrequently  the  case  that  such  "  virgin  "  soils  are  not  as 
rich  as  reported.  In  Canada,  for  example,  the  prairie  soils 
grow  as  good  crops  of  wheat  as  do  the  highly  farmed  fields 
of  England,  but  elsewhere  most  of  the  soils  treated  as  if  they 
were  fertile  virgin  soils  produce  relatively  low  wheat  yields. 

Soils  that  appear  naturally  barren  are  often  deficient 
in  water  supply,  although  excess  of  water  is  also  a  cause  of 
sterility.  A  class  of  soil  very  common  in  old  farmed  districts 
is  the  exhausted  soil.  Wheat  can  be  grown  for  many  years 
in  succession  on  the  same  land  with  a  minimum  amount  of 
manure,  but  the  yield  per  acre  gradually  falls.  Other  crops 
reach  a  state  of  exhaustion  at  a  much  greater  rate,  although 
it  has  been  found  in  many  cases  that  the  returns  can  be 
maintained  by  appropriate  treatment  and  by  application  of 
the  right  fertilizers. 

From  the  point  of  view  of  the  Industrial  Chemist,  the 
fertilizers  are  by-products  of  industry  which  proceed  to  agri- 
culture only  to  reappear  in  new  forms  of  plant  products, 
to  again  form  part  in  some  industrial  enterprise.  It  is  there- 
fore convenient  in  this  volume  of  the  series  to  begin  with  a 
discussion  of  the  fertilizers.  These  form  a  group  of  bodies 
whose  values  and  classifications  depend  on  the  uses  to  which 
they  are  put  rather  than  upon  their  origins. 

For  the  purpose  of  studying  the  fertilizers  it  is  necessary 
to  consider  more  than  one  system  of  classification. 

A  useful  general  system  will  be  to  regard  the  fertilizer 
as  a  means  of  supplying  a  particular  chemical  element  as 
follows  : — 

1.  The  nitrogen  group. 

2.  The  phosphorus  group. 

3.  The  potassium  group. 

There  will  be  many  fertilizers  that  fall  into  more  than 
one  such  group. 


4  PLANT  PRODUCTS 

There  will  also  be  the  need  to  consider  a  classification 
which  is  mainly  physical  as  follows  : — 

1.  Cementive  or  binding. 

2.  Opening  or  aerating. 

And  lastly  we  may  have  to  consider  fertilizers  from  a  dy- 
namic, rather  than  a  static  point  of  view,  as  in  the  following : — 

1.  Lasting. 

2.  Readily  available  to  the  plant. 

3.  Soluble  in  water  and  easily  diffusible. 

4.  Stimulating  and  only  suitable  for  top  dressings. 

5.  Reactive,  i.e.  those  that  induce  chemical  or  biological 
activity  in  the  soil. 

The  purely  chemical  classification,  depending  as  it  does 
upon  the  most  important  chemical  element  present,  is  com- 
paratively simple  and  devoid  of  ambiguity.  In  practice  it  is 
not  quite  so  simple  as  it  looks.  I^ater  we  shall  have  to  discuss 
cases  where  the  use  of  a  manure  dependent  for  its  value  on 
one  element  produces  ultimate  effects  which  are  best 
measured  in  terms  of  another  element.  Also  in  many  cases 
the  fertilizers  are  compound  and  contain  more  than  one 
element  of  value. 

The  physical  classification  demands  a  knowledge  of  the 
soil  to  which  the  fertilizer  is  applied.  But  the  ultimate 
physical  effects  resulting  from  the  applications  of  the 
fertilizers  are  of  a  very  varied  kind,  some  even  tending  to 
destroy  completely  the  proper  physical  condition  of  the  soil 
unless  some  remedial  measures  are  employed. 

The  power  of  a  fertilizer  to  act  quickly  or  slowly  is  a  very 
important  property.  In  some  cases  a  rapid  effect  is  desirable. 
For  example,  when  a  fertilizer  is  used  as  a  top-dressing  it 
must  always  be  soluble,  otherwise  the  action  would  be  too 
slow.  The  case  of  applying  such  a  fertilizer  as  dung  to  the 
surface  of  a  permanent  pasture  might  be  considered  a  case 
of  top-dressing,  but  this  term  is  usually  applied  to  the  use  of 
a  soluble  manure  on  a  hay  or  corn  crop  when  in  fairly  full 
growth,  under  which  circumstance  quick  action  is  necessary. 
When  a  fertilizer  is  applied  in  the  winter  or  period  of  little 
growth,  a  much  less  degree  of  solubility  will  suffice  and  it 


INTRODUCTION  5 

is  often  undesirable  to  use  a  fertilizer  that  readily  dissolves 
in  water.  Very  soluble  manures  may  actually  wash  out  of 
the  soil  before  the  plant  can  obtain  its  proper  share  of  the 
nourishment. 

In  considering  the  actions  of  fertilizers  on  the  plant  and 
on  the  soil  it  is  always  important  to  remember  that  in  no 
sense  is  such  a  series  of  actions  a  static  matter.  The  plant 
itself  is  undergoing  rapid  chemical  change  and  the  soil  is 
full  of  life.  When  a  fertilizer  is  applied  to  the  soil,  chemical 
change  begins  at  once  and  may  go  on  for  a  long  time.  These 
chemical  changes  induce  changes  in  the  development  and 
rates  of  growth  of  organisms  in  the  soil  from  the  common 
earth-worm  down  to  bacteria.  The  equilibrium  of  the  soil 
is  upset  and  will  only  be  re-established  after  an  interval 
of  time.  In  some  cases  this  interval  of  time  is  short,  but  in 
others  may  last  several  years.  In  addition  to  the  above, 
there  are  many  secondary  points  of  practical  importance. 
A  manure  to  be  successful  must  be  well  distributed.  A  little 
consideration  will  at  once  show  that  the  distribution  of 
fertilizers  is  a  difficult  problem.  There  is  no  more  important 
point  in  presenting  any  commodity  to  the  consumer  than 
placing  it  on  the  market  in  a  uniform  condition.  The  same 
point  is  just  as  true  of  the  products  of  the  field  as  of  the 
factory.  The  soil  is  not  by  any  means  uniform  by  nature, 
and  all  efforts  must  be  made  to  correct  the  irregularities 
and  not  intensify  them  by  irregular  applications  of  fertilizers. 
Soluble  fertilizers  have  the  great  advantage  that  the  rain 
distributes  them  automatically.  Unfortunately  the  distri- 
bution by  this  means  is  only  very  slight  in  a  horizontal 
direction  although  in  a  vertical  direction  it  is  much  more 
complete.  If  we  imagine  a  dressing  of  a  hundredweight  or 
so  applied  to  an  acre  and  that  all  the  grains  of  the  fertilizer 
are  about  one-tenth  of  an  inch  in  diameter,  then  there  would 
be  about  one  such  grain  for  each  square  inch.  So  that  even 
if  we  had  a  perfect  distributing  machine,  the  distribution 
of  such  a  fertilizer  would  leave  much  to  be  desired,  since  the 
root  hairs  of  the  plant  are  very  small  and  numerous,  and  if 
many  of  them  fail  to  get  their  share  of  plant  food  there  is  sure 


6  PLANT  PRODUCTS 

to  be  a  weakness  in  the  complete  plant.  Very  much  finer 
division  is  in  practice  found  to  be  necessary.  Some  years 
ago  the  author  demonstrated  on  a  small  scale  that  the  usual 
standard  sieve  for  basic  slag  was  about  right.  (See  p.  25.) 
When  a  slag  was  sieved  and  only  those  parts  which  refused 
to  pass  a  sieve  with  thirty  meshes  to  the  linear  inch  were 
used  as  a  dressing  on  grass  land,  no  visible  benefit  resulted. 
When  the  sieve  was  finer  and  contained  sixty  meshes  to  the 
linear  inch,  the  part  that  refused  to  pass  produced  a  slight 
effect.  When  the  sieve  contained  one  hundred  meshes  to 
the  linear  inch,  the  part  that  refused,  produced  about  half 
the  effect  of  a  complete  slag.  When  the  part  that  passed 
the  sieve  with  one  hundred  meshes  to  the  linear  inch  was 
applied  to  the  grass  land  the  effect  was  good ;  and  when  still 
finer  sieves  were  used,  no  further  improvement  could  be 
observed.  In  short,  so  far  as  basic  slag  on  grass  land  is 
concerned,  it  may  be  taken  as  certain  that  fertilizers  of  the 
order  of  fineness,  represented  by  just  passing  a  sieve  of  the' 
standard  dimensions,  are  at  their  maximum  efficiency. 
As  already  stated  above  fertilizers  do  not  travel  laterally 
in  the  soil,  and  in  consequence  even  the  soluble  manures 
require  some  degree  of  fine  grinding,  but  not  to  the  same 
extent  as  in  the  case  of  the  insoluble  fertilizers. 

When  the  fertilizer  is  applied,  whether  by  hand  in  broad 
casting,  or  whether  by  a  drill  or  other  machine,  it  is  desirable 
that  the  fertilizer  should  be  not  merely  finely  divided,  but 
should  also  be  in  a  dry  condition.  If  the  fertilizer  is  apt 
to  form  lumps,  all  the  energy  expended  on  fine  grinding  is 
wasted.  Materials  quite  insoluble  in  water  are  not  likely 
to  give  trouble  in  this  respect,  but  those  that  dissolve  may 
pick  up  moisture  from  damp  air,  and  the  surface  of  the  grains 
become  coated  with  a  strong  solution,  only  to  dry  up  later 
in  an  atmosphere  less  moist,  and  thus  cause  the  manure  to 
become  caked.  It  is  a  well-known  fact  that  dusty  mercury 
globules  do  not  coalesce,  and,  similarly,  it  is  a  common 
household  recipe  to  add  a  minute  amount  of  rice  flour  to 
salt,  so  that  it  does  not  cake  in  damp  weather.  The  sticky 
grains  become  coated  with  a  fine  dust,  and  are  no  longer 


INTRODUCTION  7 

able  to  cohere.  Many  forms  of  organic  matter  have  a  great 
capacity  for  absorbing  water.  This  can  be  explained  by 
reference  to  some  familiar  instances.  Ground  linseed  cake 
will  absorb  about  sixteen  times  its  weight  in  water,  peat 
moss  litter  about  ten  times  its  weight  of  water,  and  gelatine 
about  twenty  times  its  weight  of  water,  whilst  the  material 
known  as  agar,  or  dried  seaweed,  is  capable  of  retaining 
up  to  two  hundred  times  its  weight  of  water.  The  effect 
of  any  manures  of  this  class  upon  the  water  supply  of  the 
soil  is  very  pronounced.  It  will  readily  be  seen  that  a 
material  which  provides  water  for  lasting  out  a  droughty 
period  will  confer  a  great  advantage,  and  an  equal  advantage 
will  result  from  a  material  which  will  prevent  surface  washing 
of  the  soil,  by  absorbing  water  during  excessive  rainfall. 
It  is  quite  impossible  to  find  out,  except  by  experiment  on 
the  soil  itself,  what  the  value  of  any  particular  organic 
manure  may  be  as  regards  the  water-holding  capacity.  On 
very  light  soils  the  value  will  be  due  to  retention  of  water, 
and  cohesion  of  the  sandy  particles.  On  heavy  soils  the 
value  will  be  due  to  the  prevention  of  surface  washing,  by 
absorption  of  excessive  rain,  opening  up  the  soil  to  air, 
and  making  the  soil  lighter  for  spade  or  plough  to  work. 

An  important  point  in  the  consideration  of  the  use  of 
fertilizers  is  the  depth  of  penetration  of  the  manures. 
Nitrates  will  penetrate  to  practically  any  depth.  Ammonia 
compounds  are  entirely  precipitated  on  the  surface,  and  do 
not  usually  go  more  than  two  or  three  inches  deep.  Amides, 
such  as  urea  and  asparagine,  penetrate  perhaps  to  about 
ten  or  twelve  inches.  Soluble  albuminoids  penetrate  to  a 
depth  midway  between  ammonia  and  amides.  The  insoluble 
albuminoids  filter  out  on  the  surface.  Phosphates  are  precipi- 
tated near  the  surface  and  rarely  reach  a  depth  of  eight 
inches.  Super-phosphate  will  be  found  for  the  most  part 
at  a  depth  of  about  four  or  five  inches.  Basic  slag  does  not 
readily  penetrate  more  than  about  one  inch.  Potash  pene- 
trates a  little  further  than  ammonia.  This,  of  course, 
applies  only  to  the  immediate  action.  Secondary  actions 
of  all  these  materials  will  alter  their  position. 


8  PLANT  PRODUCTS 

Much  of  the  disfavour  into  which  so-called  chemical 
manures  fell  in  the  early  efforts  to  use  them  was  due  to 
injudicious  and  ignorant  use.  Probably  no  one  would  to-day 
make  the  same  mistakes,  but  to  a  lower  degree  similar 
mistakes  are  still  made.  Very  large  areas  of  land  in  many 
countries  are  urgently  in  need  of  dressings  of  lime,  because 
all  kinds  of  fertilizers  have  been  used  in  the  past,  with  only 
a  partial  recognition  of  the  important  fact  that  most  ferti- 
lizers remove  lime  from  the  soil.  In  the  early  days  of  inten- 
sive farming  lime  was  used  generously  and  often  excessively. 
No  doubt  the  disastrous  effects  of  excessive  use  of  lime 
made  farmers  rush  to  the  opposite  extreme,  and  use  far  too 
little  lime.  To-day  we  have  to  make  up  for  past  neglect. 
Even  on  soils  which  stand  over  chalk  or  other  calcareous 
geological  formations,  lime  is  not  infrequently  advantageous. 

All  life  depends  on  a  delicate  balance  of  chemical  reactions, 
and  although  living  things  have  a  considerable  power  of 
resistance,  if  one  is  merely  considering  them  from  the 
point  of  view  of  the  struggle  for  existence,  yet  when  one  is 
considering  the  growth  of  plants  from  the  point  of  view  of 
obtaining  a  paying  crop,  one  cannot  permit  them  to  struggle, 
one  must  supply  them  with  the  balance  which  they  require. 
Unfortunately,  this  problem  of  the  balance  of  the  ingredients 
needed  by  the  plants  has  received  too  little  attention. 
The  way  in  which  the  balance  of  a  soil  may  be  upset  is  shown 
in  the  following  graph,  which  is  taken  from  a  paper  by  the 
author,  read  to  the  Society  of  Chemical  Industry,  May  31, 
1915.  This  graph  shows,  with  regard  to  the  two  constituents 
selected  for  illustration,  that  when  the  fertilizing  dressing 
of  magnesia  or  manganese  increased,  an  increase  in  crop 
occurred  at  first,  but  after  moderate  percentages  of  the 
fertilizing  ingredients  had  been  used,  a  decrease  in  crop 
occurred.  There  are  any  number  of  illustrations  of  the 
same  law,  in  other  subjects  dealing  with  the  life  of  -plants 
or  animals. 

All  the  more  recent  books  to  be  found  in  the  bibliography, 
have  some  reference  to  the  principle  that  the  balance  of 
the  ingredients  is  an  important  proposition. 


INTRODUCTION  9 

The  plant  products  thus  obtained  are  rarely  fit  for 
immediate  use  and  have  to  undergo  fuither  manipulations. 
Sometimes  crops  are  fed  to  cows  which  give  milk  which 

GRAPH. 

Correlation  between  the  Hay  Crop  and  MgO%  =  x  or  MnO%  =  o 
Below  Mean  %.  Above  Mean  %. 


«a 

§  >       *05 


o  S     .05 


Is 

w 


p  * 


I    %MnO  »l -5 


is  turned  into  cheese,  or  other  products.  There  is  therefore 
hardly  any  ultimate  limit  to  the  subject  of  plant  products, 
and  sooner  or  later  they  all  appear  in  some  other  volume 
of  this  series. 


REFERENCES    TO   INTRODUCTION 

Daubeny,  "  Roman  Husbandry"  (Oxford)  (from  Columella  and  Virgil). 

Davy,  "Agricultural  Chemistry"  (Griffin)  (1802-12). 

Liebig,  "Chemie  fur  Agricultur  u.  Physiologic  "  (Vieweg)  (about  1840). 

Boussingault,  "Agronomic,  Chimie  Agricole  et  Physiologic"  (Mallet- 
Bachelier)  (about  1850). 

Collins  and  Hall,  "The  Inter-relationships  between  the  Constituents 
of  Basic  Slag,"  Journ.  Soc.  Chem.  Ind.,  May,  1915,  p.  526. 


PART  I.— THE    FERTILIZERS 


SECTION  I.— NITROGEN    GROUP    OF 
FERTILIZERS 

THE  nitrogen  fertilizers  have  certain  properties  in  common. 
Most  fertilizers  in  this  group  contain  the  element  nitrogen 
in  a  fairly  available  form  and  do  not  contain  any  large  amount 
of  either  phosphorus  or  potassium.  They  all  tend  to  stimulate 
the  active  growth  of  the  plant  especially  as  regards  the  green 
parts  thereof.  A  general  tendency  of  this  group  is  to  delay 
ripening,  a  result  not  always  beneficial.  If  applied  too  freely 
they  may  cause  corn  to  "  lodge,"  that  is  to  grow  too  big 
and  heavy  for  the  stem  to  properly  support  the  ears.  In  the 
case  of  plants  bearing  fruit  the  result  of  too  liberal  dressings 
of  nitrogenous  fertilizers  may  result  in  too  large  development 
of  leaf  or  woody  stem  with  a  resultant  loss  of  fruit.  Used 
with  discretion  this  group  of  fertilizers  provides  one  of  the 
most  valuable  means  of  obtaining  large  increases  in  the 
crops  produced. 

That  there  is  a  considerable  degree  of  interchangeability 
between  the  members  of  this  group  may  be  seen  in  Table  i. 

TABLE  i. — NITROGEN  STIMULANTS. 
Results  of  field  experiments  on  grain.     Crop  per  acre. 


Manure. 

Order 
of 
merit. 

Average  of  thirteen 
experiments. 

r     .            Straw 
Gram-     and  chaff. 

6 
5 

2 

4 

I 

3 

Ibs. 
2196 
226o 

2595 
2668 
2680 
2816 
2697 

cwts. 

271 
29 

35i 
37 

& 

35* 

2.  Super-phosphate  and  potash 
3.  No.  2  and  nitrate  of  soda  .  . 
4.  No.  2  and  sulphate  of  ammonia  .  . 
5.  No.  2  and  calcium  cyanamide  (early  application) 
6.  No.  2  and  nitrate  of  lime  .  . 
7.  No.  2  and  calcium  cyanamide  (late  application) 

NITROGEN   GROUP  OF  FERTILIZERS         n 

It  will  be  seen  that  the  effect  of  the  nitrogenous  fertilizers 
is  in  all  cases  a  very  marked  one,  that  some  give  better  results 
than  others,  but  the  different  forms  of  nitrogenous  manures 
will  not  always  fall  in  this  order,  although  for  cereal  crops 
it  may  be  expected  that  something  like  this  order  will  be 
maintained. 

The  general  subject  of  the  nitrogen  fertilizers  cannot  be 
discussed  without  some  reference  to  the  possible  alternate 
scheme  of  producing  the  nitrogen  needed  on  the  farm  by 
indirect  means,  although  this  subject  can  be  better  discussed 
in  Part  IV. 

By  the  use  of  phosphatic  manures  it  is  possible  to  develop 
the  growth  of  leguminous  plants  which  indirectly  extract 
nitrogen  from  the  air.  The  nitrogen  so  extracted  will  not 
all  be  sold  off  as  crop,  some  will  remain  in  the  soil  as  the  roots 
of  the  leguminous  plant.  When  the  leguminous  plants  are 
fed  to  stock,  most  of  the  nitrogen  will  find  its  way  into  the 
manure  heap  and,  provided  that  care  be  taken,  thence  to 
the  soil.  Such  accumulations  will  be  slow  acting  and  can 
never  entirely  replace  the  quick-acting  nitrogenous  ferti- 
lizers ;  nevertheless  great  economy  of  nitrogenous  fertilizers 
is  possible  by  these  means. 

At  the  present  time  war  has  drawn  attention  to  many 
methods  for  the  fixation  of  atmospheric  nitrogen.  When  the 
war  is  over  and  the  demand  for  explosives  slackens,  the 
synthetic  nitrogen  compounds  will  be  more  extensively 
used  for  agricultural  purposes. 

Sulphate  of  Ammonia. — Sulphate  of  ammonia  is  a 
product  of  gas  works  and  coke  ovens.  The  amount  obtained 
in  practice  is  by  no  means  what  could  be  obtained  under 
theoretical  conditions ;  for  example,  the  ordinary  gas 
retort  gives  little  more  than  twenty  pounds  of  sulphate 
of  ammonia  per  ton  of  coal  carbonized,  whereas  theoretically, 
one  hundred  and  fifty  pounds  of  sulphate  of  ammonia  per 
ton  of  coal  carbonized  might  be  obtained.  There  are, 
therefore,  great  possibilities  of  an  increase  in  the  amount 
of  sulphate  of  ammonia  available  for  agricultural  purposes. 
Sulphate  of  ammonia  has  for  many  years  past  been  obtainable 


12  PLANT  PRODUCTS 

at  prices  varying  from  about  fy  to  £20  per  ton  at  British 
ports.  Roughly  speaking  £14  per  ton  is  considered  a  general 
average  of  English  prices. 

The  demand  for  sulphate  of  ammonia  for  agricultural  pur- 
poses is  almost  certain  to  increase,  as  the  need  for  it  is  better 
recognized.  That  the  value  of,  say,  £14.  per  ton  is,  from  the 
user's  point  of  view,  not  an  unreasonable  one,  may  be  judged 
from  Table  2,  which  is  based  on  recent  field  experiments  and 
shows  the  average  increase  in  the  various  crops  with  the  value 
of  such  increase  that  may  be  expected  from  the  use  of  i  cwt. 
of  sulphate  of  ammonia  per  acre,  costing  about  seventeen 
shillings.  The  crops  have  been  valued  at  low  prices. 

TABLE  2. 


Increase  due  to  i  cwt.  sulphate  of  ammonia  costing  175. 
Wheat  Straw. 


£     s.     d.       £     s.     d. 

Wheat  .         4  bush,  at  555.  per  qr.  504  Ibs.       i       7     6    I    T     17     5 

5  cwt.  at  405.  per  ton  . .     o     10    o    ' 


Barley 
Barley  Straw. 
Oats    .. 
Oat  Straw 


Meadow  Hay. 

Mangolds 

Potatoes 


6  bush,  at  505.  per  qr.  448  Ibs.       i     17     6 

6  cwt.  at  305.  per  ton 

7  bush,  at  305.  per  qr.  336  Ibs 
7  cwts.  at  405.  per  ton 


Rye  Grass  Hay     10  cwts.  at  loos,  per  ton 


8  cwts.  at  QOS.  per  ton 
32  cwts.  at  I2s.  6d.  per  ton 
20  cwts.  at  6os.  per  ton 


090 
i  6  3 
0140 


2  10  O 

I  16  o 

I  O  O 

3  o  o 


Consideration  of  the  foregoing  figures  shows  that  there 
is  ample  justification  for  the  liberal  use  of  reliable  manures. 

For  practical  purposes  sulphate  of  ammonia  may  either 
be  applied  by  itself  or  in  mixtures.  Probably  most  of  the 
sulphate  of  ammonia  actually  used  is  applied  in  mixtures, 
either  made  by  the  farmer  himself  or  purchased  ready  made 
from  the  manufacturer. 

Certain  of  these  mixtures  are  very  practicable  and  useful, 
others  are  not  desirable,  and  others  must  be  avoided  at  all 
costs. 

One  of  the  commonest  and  most  useful  mixtures  is  com- 
pounded from  sulphate  of  ammonia  and  super-phosphate. 
This  mixture  has  the  following  special  advantages  : — both 
manures  are  moderately  quick  in  action ;  neither  are 
instantly  available  for  plant  life. 


NITROGEN  GROUP  OF  FERTILIZERS         13 

In  both  cases  changes  have  to  take  place  in  the  soil 
before  the  constituents  of  the  fertilizer  are  suitable  for 
absorption  by  the  plant ;  indeed,  in  both  cases  a  water  culture 
of  either  super-phosphate  or  sulphate  of  ammonia,  or  both 
together,  would  be  absolutely  injurious  to  the  plant,  and  the 
plant  would  probably  refuse  to  grow  altogether.  After, 
however,  these  materials  have  acted  upon  the  soil  they  are 
rendered  suitable  to  the  plant's  needs. 

When  sulphate  of  ammonia  acts  upon  ths  soil  a  complete 
chemical  change  takes  place.  This  change  can  be  easily 
demonstrated  so  far  as  the  broad  effects  are  concerned  by 
the  following  simple  experiment : — A  couple  of  glass  tubes, 
about  2 1  or  3  inches  in  diameter,  and  about  a  foot  in  length, 
are  partially  closed  at  one  end  with  cork ,  and  cotton-wool, 
and  a  depth  of  6  or  8  inches  of  soil  placed  in  the  tubes. 
Into  one  tube  is  poured  some  distilled  water  so  as  to  perceive 
the  effect  of  plain  water  upon  the  soil ;  into  the  other  tube 
is  poured  a  solution  of  sulphate  of  ammonia  in  water.  If 
a  quantity  of  sulphate  of  ammonia  weighing  about  one- 
tenth  of  a  gramme  be  used  for  one  of  these  tubes  it  would 
correspond  to  an  application  of  2  cwt.  sulphate  of  ammonia 
per  acre,  a  quantity  comparable  to  practice. 

A  litre  of  water  poured  on  to  the  quantity  of  soil  men- 
tioned above  would  correspond  to  a  rainfall  of  about  ten 
inches. 

If  the  drainage  from  the  two  tubes  be  now  collected,  the 
addition  of  a  small  quantity  of  "  Nessler's,"  solution  will 
give  a  coloration  due  to  the  ammonia,  and  it  will  be  at  once 
observed  that  whilst  the  original  manure  employed  shows 
a  large  amount  of  ammonia  present,  the  drainage  from  the 
manured  soil  only  shows  a  fraction  of  that  amount.  The 
distilled  water  itself  will  be  found  to  have  washed  a  little 
ammonia  out  of  the  soil,  unless  the  soil  chosen  was  a 
particularly  poor  one.  We  perceive  at  once  from  such  an 
experiment  that  the  ammonia  has  in  some  way  been  removed 
from  aqueous  solution,  or  in  other  words,  the  ammonia 
has  been  fixed  by  the  soil.  These  fixations  of  fertilizer 
ingredients  are  always  partial  reactions  which  follow  the 


14  PLANT  PRODUCTS 

chief  chemical  laws  of  mass  action,  so  that  the  soil  water 
will  always  take  away  some  ammonia  from  the  soil. 

After  the  ammonia  has  become  fixed  hi  the  soil  it  still  has 
to  undergo  further  changes.  These  changes  are,  however, 
not  purely  chemical  ones,  but  are  dependent  upon  bacterial 
action,  and  are  not  so  easily  demonstrated  on  the  lecture 
table  or  in  the  laboratory.  They  require  an  elaborate  experi- 
ment on  the  field  itself.  Such  elaborate  field  experiments 
have  been  carried  out  at  Rothamsted. 

To  return  to  our  experiment  with  two  tubes,  another 
point  that  can  be  easily  investigated  by  such  an  experiment 
is  to  examine  the  fate  of  the  sulphuric  acid  part  of  the  sulphate 
of  ammonia. 

By  the  use  of  barium  chloride  we  can  see  at  once  that  plain 
water  removes  a  noticeable  amount  of  sulphuric  acid  from 
the  soil,  and  that  the  drainage  from  the  manured  soil 
practically  amounts  to  the  sum  of  the  other  two  quantities, 
namely,  that  which  sulphate  of  ammonia  contains  and  that 
which  water  washes  out  of  the  unmanured  soil.  Another 
very  important  result  that  can  be  seen  from  this  experiment 
is  the  effect  of  the  sulphate  of  ammonia  on  the  amount  of 
lime  in  the  soil.  The  sulphuric  acid  part  of  the  sulphate 
of  ammonia  combines  with  the  lime  in  the  soil  and  the  two 
go  out  together  as  calcium  sulphate.  A  test  with  ammonium 
oxalate  on  the  drainage  from  the  two  tubes  will  show  at 
once  that  the  lime  lost  to  the  soil  by  drainage  is  very  much 
greater  when  sulphate  of  ammonia  is  applied  than  when  the 
soil  is  unmanured.  In  common  agricultural  language, 
sulphate  of  ammonia  exhausts  the  soil  of  its  lime.  The 
demonstration  of  this  point  on  a  large  scale  in  the  field  has 
been  very  admirably  shown  in  the  researches  of  the  Royal 
Agricultural  Society  in  their  experimental  farm  at  Woburn. 
In  certain  plots  of  barley  continuous  application  of  sulphate 
of  ammonia  results  in  turning  a  light  but  good  soil  into  a  mere 
desert,  which  grows  nothing  at  all,  except  an  occasional 
weed.  When,  however,  soil,  which  has  been  rendered 
infertile  by  deliberate  over-manuring  is  subsequently  treated 
to  a  dressing  of  lime,  the  fertility  is  recovered,  and  crops 


NITROGEN   GROUP  OF  FERTILIZERS         15 

grow  once  again.  The  success  of  application  of  sulphate 
of  ammonia  is,  therefore,  intimately  connected  with  the 
amount  of  lime  which  is  either  naturally  present  in  the  soil, 
or  has  been  added  to  the  soil. 

Without  the  lime,  sulphate  of  ammonia  will  not  undergo 
those  changes  which  are  necessary.  The  amount  of  sulphate 
of  ammonia  which  can  be  applied  to  the  soil  may  be  put  down 
roughly  as  one  or  two  hundredweight  per  acre. 

For  the  purpose  of  enabling  a  wheat  crop  to  get  over  the 
dangerous  period  either  at  the  beginning  or  the  end  of  the 
winter  a  top  dressing  of  sulphate  of  ammonia  is  most  useful. 
For  such  purposes  as  top  dressings  only  about  half  a  cwt. 
of  sulphate  of  ammonia  need  be  used  at  one  time,  as  it  is 
not  difficult  to  give  a  second  dressing  of  J  cwt.  later  on  should 
it  be  found  necessary.  The  farmer  will  judge  for  himself 
from  the  look  of  the  crop  whether  such  an  application  is 
desirable  or  not.  Should  the  plant  appear  yellow  and  sickly 
it  is  a  safe  thing  to  give  a  top  dressing.  Another  great  use 
of  top  dressings  of  sulphate  of  ammonia  is  to  enable  a  growing 
crop  or  slow  crop  to  get  through  a  droughty  period  when  half 
grown.  As  explained  in  Part  III.,  Section  I.,  an  application 
of  fertilizer  may  be  equivalent  to  an  application  of  water, 
and  of  the  manures  which  can  be  used  in  this  way  sulphate 
of  ammonia  takes  a  very  important  position.  Such  small 
dressings  as  are  here  referred  to  undoubtedly  present  some 
difficulty  in  their  even  distribution,  but  the  sulphate  of 
ammonia  can  be  mixed  with  a  small  quantity  of  dry  earth 
or  ashes,  but  not  with  lime  or  any  substance  containing 
lime. 

Use  of  sulphate  of  ammonia  demands  some  knowledge 
of  the  general  physical  and  chemical  properties  of  the  sub- 
stance. Commercial  sulphate  of  ammonia  is  a  very  finely 
cry&tallized  substance,  having  a  slight  tendency  to  stick 
together,  owing  to  the  presence  of  two  or  three  per  cent,  of 
water,  and  a  few  tenths  of  a  per  cent,  of  free  sulphuric  acid. 
It  does  not,  however,  exhibit  any  great  tendency  to  cake, 
but  may  need  to  be  broken  by  a  spade  before  use.  It  is  very 
easily  soluble  in  water,  and  the  common  article  will  just  redden 


16  PLANT  PRODUCTS 

a  piece  of  blue  litmus  paper.  When  heated  it  gives  up  the 
small  amount  of  water  which  it  contains,  and  then  proceeds 
to  undergo  a  regular  and  complete  decomposition.  At  first 
sulphate  of  ammonia  decomposes  into  ammonia  and 
ammonium  hydrogen  sulphate,  then  splits  off  some  sulphur 
tri-oxide,  which  reacts  as  an  oxidizing  agent,  giving  off 
free  nitrogen  and  sulphur  dioxide.  The  sulphur  dioxide, 
together  with  the  water,  and  some  of  the  free  ammonia, 
then  again  combine  and  produce  ammonium  hydrogen 
sulphite.  These  reactions  can  easily  be  perceived  when 
ammonium  sulphate  is  slowly  heated  in  a  test-tube.  The 
water  coming  off  will  at  first  condense  in  the  colder  and  upper 
part  of  the  test-tube ;  further  heating  results  in  giving  off 
a  smell  of  ammonia,  and  in  the  formation  of  a  sublimate  in 
the  colder  part  of  the  test-tube.  If,  after  cooling,  one  or 
two  drops  of  hot  water  be  added  to  the  contents  of  the  test- 
tube,  a  smell  of  sulphur  dioxide  is  at  once  perceived,  because 
the  ammonium  hydrogen  sulphite  is  not  a  very  stable 
body,  but  dissociates  with  hot  water.  The  ultimate  result 
of  heating  sulphate  of  ammonia  is  that  the  water,  ammonia, 
and  sulphuric  acid  are  driven  off,  and  nothing  left  behind 
but  some  mineral  impurity  which  is  mostly  a  trace  of  soil 
or  iron  oxide. 

When  sulphate  of  ammonia  comes  into  contact  with  an 
alkali  or  strong  base,  the  sulphuric  acid  combines  with  the 
alkali  or  base,  and  the  ammonia  is  set  free  and  diffuses  into 
the  atmosphere.  It  is  for  these  reasons,  that  sulphate  of 
ammonia  should  never  be  mixed  with  lime,  wood  ashes, 
or  basic  slag.  However,  very  few  soils  are  so  calcareous 
that  the  clay  and  humus  do  not  greatly  preponderate  over 
the  lime,  so  that  the  ammonia  is  more  readily  fixed  by  the 
clay  and  the  humus  than  it  is  driven  off  by  the  lime  materials. 
Sulphate  of  ammonia  will  take  three  weeks  of  very  good 
weather  to  nitrify  all  the  ammonia  added  to  the  soil. 
Nitrification,  though  very  slow  in  the  winter,  produces  some 
nitrate  which  is  lost  by  drainage,  though  such  loss  is  not 
sufficient  to  condemn  the  winter  application  of  sulphate 
of  ammonia.  On  general  grounds  sulphate  of  ammonia 


NITROGEN  GROUP  OF  FERTILIZERS          17 

must  be  regarded  as  a  manure  to  be  applied  shortly  before 
it  is  needed.  It  is  not  so  quick  in  its  action  as  nitrate  of 
soda  or  nitrate  of  lime,  but  is  a  great  deal  quicker  than  the 
organic  nitrogen  manures.  Its  stimulating  effects  on  the 
plant  are  seen  in  the  large  development  of  the  leaf.  It  is 
therefore  especially  valuable  for  the  production  of  green 
stuff,  and  is  deservedly  very  popular  among  market  gardeners 
and  all  intensive  cultivators.  For  the  purpose  of  fruit 
growing  it  is  not  such  a  suitable  manure,  since  some  fruits 
do  not  develop  well  if  the  plant  is  too  vigorous  and  rank 
in  its  growth.  Such  prolific  fruits  as  gooseberries  must  be 
excepted  from  this  general  statement  (see  p.  166). 

Sulphate  of  ammonia,  in  a  very  crude  form,  occurs  in 
soot  (see  pp.  66  and  92). 

Ammonium  Chloride. — Of  the  other  compounds  of 
ammonia  which  have  been  used  as  fertilizers  ammonium 
chloride  is  probably  the  most  important.  Ammonium 
chloride,  sal  ammoniac,  or  muriate  of  ammonia,  has  always 
been  used  in  the  Rothamsted  experiments,  doubtless  because 
at  the  date  when  these  experiments  were  started  it  was  by 
no  means  a  foregone  conclusion  which  particular  ammonia 
salt  would  prove  most  practicable.  When  ammonium 
chloride  is  used  as  a  manure  many  of  the  soil  reactions 
closely  resemble  those  of  the  sulphate.  The  ammonia  is 
fixed  in  the  soil,  the  chlorine  carries  away  calcium  (lime), 
so  that  the  ultimate  result  in  the  soil  is  the  same.  The 
actions  of  sulphates  and  chlorides  on  plant  life  are  nearly 
but  not  quite  identical,  though  these  points  can  better  be 
discussed  under  the  heads  of  the  crops  concerned  (see 
Part  III.).  At  the  present  time  there  does  not  seem  any 
likelihood  that  ammonium  chloride  will  be  a  practicable 
fertilizer. 

Ammonium  Nitrate. — Ammonium  nitrate  is  a  very 
deliquescent  substance,  and  is  for  that  reason  not  very 
suitable  as  a  fertilizer.  Its  very  high  percentage  of  nitrogen, 
however,  might  make  it  valuable  where  transport  facilities 
were  very  poor.  Though,  at  present  this  does  not  seem 
a  very  practicable  manure,  it  would  certainly  have  the 
D.  2 


i8  PLANT  PRODUCTS 

advantage  that  there  is  nothing  in  it   of  an  objectionable 
character. 

Ammonium  Carbonate. — Ammonium  carbonate  itself 
is  too  volatile,  but  ammonium  hydrogen  carbonate  is  a 
light,  dry  powdery  substance,  which  only  slightly  smells 
of  ammonia.  At  present  no  serious  attempt  has  been  made 
to  produce  ammonium  bi-carbonate  for  use  as  a  fertilizer, 
but  since  the  gas  works  have  already  prepared  directly  a 
strong  liquid  ammonia  there  does  not  seem  any  reason  why 
they  should  not  manufacture  ammonium  hydrogen  carbonate, 
as,  of  course,  it  is  obvious  that  they  produce  carbonic  acid 
in  quantities  many  thousands  of  times  more  than  is  needed 
for  this  purpose.  At  present,  however,  this  also  is  not  a 
practicable  fertilizer. 

Nitrate  of  Soda. — Nitrate  of  soda  chiefly  occurs  as 
a  deposit  in  Chili,  is  mined,  extracted  with  water,  and  re- 
crystallized.  The  composition  is  fairly  constant,  containing 
rarely  less  than  93  per  cent,  pure  nitrate  of  soda,  or  more  than 
97  per  cent.  pure.  Of  a  large  number  of  samples  examined, 
over  one  half  had  between  96  and  97  per  cent,  pure  nitrate 
of  soda.  As  it  is  obtained  exclusively  from  foreign  sources 
it  is  imported  by  ship,  and  as  a  rule  the  shipments  are  of 
a  definite  known  composition.  Nitrate  of  soda  does  not 
lend  itself  very  particularly  well  to  mixtures.  It  can  be 
mixed  with  basic  slag,  but  such  a  mixture  is  not  particularly 
useful,  because  nitrate  of  soda  is  very  quick  acting,  and  basic 
slag  is  very  slow.  It  cannot  be  mixed  at  all  satisfactorily 
with  super-phosphates,  since  this  mixture  becomes  somewhat 
heated  and  produces  free  nitric  acid,  which  then  distils 
out  of  the  mass  and  condenses  on  the  outer  surface  and  thus 
rots  the  bags  or  sacks  which  may  have  been  used  for  transport. 
The  chief  method  of  application  of  nitrate  of  soda  to  the  soil 
is  for  a  top  dressing,  as  it  need  not  undergo  any  chemical 
change  in  the  soil  before  absorption  by  the  plant.  It  is 
applied  as  a  top  dressing  in  the  same  way  as  sulphate  of 
ammonia,  and  is  among  the  quickest  of  all  fertilizers. 
Nitrate  of  soda  as  sent  to  the  farmer  is  not  infrequently  in 
large  lumps,  and  requires  to  be  broken  up.  Owing  to  its 


NITROGEN  GROUP  OF  FERTILIZERS         19 

extreme  solubility  in  water,  it  must  be  kept  dry,  and  owing 
to  its  deliquescent  properties  it  must  be  kept  away  even  from 
moist  air.  If  it  becomes  very  damp  it  is  likely  to  cake 
together  and  to  need  breaking  up  again  before  application. 
When  applied  to  the  soil  a  slight  chemical  change  takes 
place.  To  a  limited  extent  the  soda  in  nitrate  of  soda  and 
the  lime  in  the  soil  change  places  with  one  another. 
Continuous  application  of  nitrate  of  soda  will  therefore 
remove  lime  from  the  soil  by  drainage.  Nitrate  of  soda 
does  not,  however,  remove  quite  so  much  lime  as  sulphate 
of  ammonia.  Whilst  sulphate  of  ammonia  contains  the 
relatively  unimportant  ingredient  sulphuric  acid,  nitrate 
of  soda  contains  the  equally  unimportant  ingredient  soda. 
The  former,  of  course,  produces  an  acid  reaction,  and  the 
latter  produces  an  alkaline  reaction.  Whilst  the  sulphate 
of  lime  produced  from  sulphate  of  ammonia  readily  drains 
away  from  the  soil,  in  the  case  of  the  soda  the  loss  by  drainage 
is  less  rapid.  The  soda  acts  chiefly  upon  the  clay  and  humus 
of  the  soil,  and  forms  a  colloidal  solution,  which  results  in 
the  transfer  of  the  fine  clay  particles  from  the  surface  to 
the  sub-soil,  reducing  the  fertility  of  the  surface  soil,  whilst 
the  sub-soil  becomes  choked  with  material  more  or  less 
impervious  to  water.  From  the  above  causes  both  sulphate 
of  ammonia  and  nitrate  of  soda,  when  used  in  large  excess, 
as  in  the  Woburn  experiments,  produce  almost  equally 
bad  results.  The  cure  for  these  objectionable  effects  from 
nitrate  of  soda  lies  in  the  use  of  lime  or  sulphate  of  lime. 
The  former  can  be  supplied  in  basic  slag,  and  the  latter  in 
super-phosphates.  The  chief  effect  of  the  use  of  nitrate 
of  soda  upon  the  crop  grown  is  to  stimulate  the  production 
of  green  stuff.  Hence  it  is  of  particular  value  for  such 
crops  as  gooseberries,  cabbages,  and  turnips.  L,ike  sulphate 
of  ammonia,  it  may  also  be  used  as  a  top  dressing  for 
application  either  to  wheat  or  to  hay.  Both  of  these  manures, 
sulphate  of  ammonia  and  nitrate  of  soda,  are  much  used  in 
intensive  forms  of  tropical  agriculture,  on  such  crops  as 
tobacco  and  coffee.  The  impurities  in  nitrate  of  soda 
include  potassium  iodide,  potassium  iodate,  and  potassium 


20  PLANT  PRODUCTS 

perchlorate.  It  frequently  happens  that  there  is  quite 
enough  iodine  to  produce  a  smell  of  that  element,  and  traces 
of  perchlorate  are  also  common.  Cases  have  been  recorded 
where  these  impurities  have  reached  sufficient  amounts  to 
produce  prejudicial  effects  on  the  crops  grown,  but  the  event 
is  too  rare  to  be  of  any  practical  importance.  The  effects 
of  rare  elements  like  iodine  can  be  studied  in  the  Royal 
Agricultural  Society's  Reports. 

Nitrate  of  Lime. — In  1898  Sir  William  Crookes  read 
his  Presidential  address  to  the  British  Association  at  Bristol, 
calling  attention  to  the  possible  diminution  in  the  world's 
supply  of  wheat,  and  urged  the  necessity  of  the  manufacture 
of  nitrates  directly  from  the  air.  It  is  taking  a  long  time 
to  reach  the  condition  of  affairs  he  described,  though  the 
world's  shortage  of  wheat  is  certainly  already  appearing.  The 
supply  of  nitrate  of  soda  has  not  shown  the  decrease  antici- 
pated ;  on  the  other  hand,  sulphate  of  ammonia  has  proved 
to  be  more  plentiful,  but,  nevertheless,  some  nitrate  made 
from  the  air  is  now  a  practical  fertilizer  and  after  the  war 
is  over  may  come  into  more  general  use.  The  chief  difficulty 
in  using  nitrate  of  lime  is  due  to  its  deliquescent  properties  ; 
nitrate  of  soda  is  bad  enough  in  this  respect,  but  nitrate 
of  lime  is  worse.  Nitrate  of  lime  has  to  be  kept  in  casks, 
which  are  by  no  means  convenient  to  carry  to  the  field. 
When  nitrate  of  lime  is  broadcast  by  hand  it  is  extremely 
unpleasant  to  the  workers,  since  small  dust  particles 
settle  upon  the  workers'  faces,  and  by  dissolving  in  traces 
of  sweat,  produce  a  stinging  strong  solution.  Nitrate  of 
lime  can  be  used  in  much  the  same  way  as  nitrate  of  soda. 
It  is  very  quick  acting,  should  only  be  used  as  a  top  dressing, 
is  instantly  available,  and  is  easily  washed  out  of  the  soil. 
When  nitrate  of  lime  is  mixed  with  a  small  proportion  of 
sulphate  of  ammonia,  a  very  fine  dry  breadcrumb-like 
powder  is  obtained,  which  is  very  convenient  to  handle. 
Nitrate  of  lime  cannot  be  mixed  with  super-phosphate 
(see  p.  35),  and  admixture  with  basic  slag  would  be  of  little 
value.  One  of  its  great  advantages  lies  in  the  fact  that  it 
has  no  useless  ingredients  ;  the  whole  of  the  lime  and  the 


NITROGEN  GROUP  OF  FERTILIZERS         21 

nitrate  can  be  easily  absorbed  by  the  plant,  and  nothing 
is  left  behind  in  the  soil,  either  good  or  evil.  It  therefore 
is  especially  suited  to  conditions  of  drought  01  bad  drainage 
where  undesirable  salts  accumulate  and  cannot  be  removed. 
Ivike  nitrate  of  soda,  it  is  quite  unsuitable  for  winter 
application. 

Nitrate  of  Potash. — Nitrate  of  potash,  or  potassium 
nitrate,  is  one  of  the  earliest  artificial  manures.  In  the 
vicinity  of  old  village  sites  nitre  earths  are  of  comparatively 
frequent  occurrence,  especially  in  India  and  Egypt.  In 
India  the  collection  and  working  of  these  is  an  old-established 
industry.  The  nitre  earths,  which  have  accumulated  as 
the  result  of  the  decomposition  of  organic  nitrogenous  waste, 
are  put  into  small  pits  with  false  bottoms  and  extracted 
with  a  minimum  possible  quantity  of  water.  The  solution 
obtained  is  then  crystallized,  and  crude  nitrate  of  potash 
obtained.  Both  the  original  nitre  earths  and  the  waste 
from  this  crude  manufacture  are  used  regularly  for  ordinary 
manuring  of  crops.  In  some  localities  also,  considerable 
accumulations  of  nitrate  of  potash  occur  in  the  well  waters, 
and  some  of  the  districts  in  India  which  grow  tobacco  crops 
are  situated  in  areas  where  there  are  many  nitre  wells. 

The  manufacture  of  pure  nitrate  of  potash  from  the 
above  crude  materials  has  been  brought  to  such  a  state  of 
perfection  that  the  waste  contains  very  little  potash  or 
nitric  acid. 

Nitrate  of  potash  is,  of  course,  a  very  valuable  manure, 
as  it  contains  two  elements  of  value  to  the  plant.  When 
added  to  the  soil  the  potash  combines  with  the  clay  and  humus 
and  becomes  fixed,  and  the  nitric  acid  combines  with  the  lime 
in  the  soil  (see  also  Potassium  Manures,  p.  37). 

Calcium  Cyanamide.  — The  manufacture  consists,  firstly 
in  producing  calcium  carbide,  which  is  made  in  an  electric 
furnace  from  lime  and  coke.  The  calcium  carbide  is  then 
heated,  and  nitrogen  passed  through  it,  when  calcium 
cyanamide  and  graphite  are  produced.  The  material  put 
upon  the  market  contains  about  50  to  55  per  cent,  calcium 
cyanamide,  25  to  30  per  cent,  lime  n  to  12  per  cent,  graphite, 


22  PLANT  PRODUCTS 

and  2  to  3  per  cent,  silica.  The  amount  of  nitrogen  varies 
from  17  to  20  per  cent.  Calcium  cyanamide,  when  kept  in 
store,  slowly  absorbs  water  from  the  air,  so  that  it  increases 
in  weight.  In  consequence  of  this  fact  the  percentage  of 
nitrogen  decreases  at  the  rate  of  i  per  cent,  in  two  or  three 
months,  but  the  owner  does  not  thereby  lose  anything. 
At  the  same  time  a  small  amount  of  decomposition  does  take 
place,  and  traces  of  ammonia  are  given  out  into  the  air. 
Calcium  cyanamide  in  itself  is  no  use  to  the  plant,  and  when 
acted  upon  by  the  water  in  the  soil  it  will  produce  the  poison 
di-cyanamide,  which  will  slowly  decompose  into  ammonia, 
and  then  nitrify.  It  is  only  suitable  for  application  some 
time  before  sowing.  It  is  a  slow-acting  manure,  and  is  quite 
unsuited  to  top  dressing.  It  can  be  mixed  with  basic  slag, 
but  not  with  super-phosphate  or  with  sulphate  of  ammonia. 
The  amount  of  lime  present  is  generally  beneficial,  and  the 
graphite  is  absolutely  harmless.  At  first  calcium  cyanamide 
will  act  as  a  poison ;  it  will  therefore  have  the  value  which 
will  be  alluded  to  again  under  the  head  of  the  "  Partial 
Sterilization  of  Soils  "  (see  p.  90). 

The  Organic  Nitrogen  Fertilizers. — Fish  refuse,  fish 
meal,  or  fish  guano,  is  one  of  the  most  important  in  this 
group. 

Refuse  fish  is  often  used  locally  by  farmers,  but  the 
manufacture  of  fish  meal  and  fish  guano  are  definite  industries 
in  connection  with  fisheries.  The  best  qualities  are  used  only 
for  feeding  purposes,  but  the  other  qualities  are  applied  to 
the  soil.  A  very  large  proportion  of  the  fish  guano  in  Great 
Britain  comes  from  herrings.  The  heads,  tails,  and  guts 
that  are  discarded  in  salting  the  herrings  are  dried,  and 
then  the  fat  extracted  by  petroleum  spirit.  The  resulting 
material  when  used  for  fish  guano  contains  about  9  to  12  per 
cent,  nitrogen,  3  to  5  per  cent,  of  phosphoric  acid,  and  about 
i  per  cent,  of  potash.  The  amount  of  oil  should  not  exceed 
i  to  2  per  cent.  In  other  parts  of  the  world  other  systems 
are  often  in  use.  In  some  parts  of  America  the  fish  is  boiled, 
the  fat  skimmed  off,  and  the  resulting  mass  dried  and  used 
as  a  manure.  In  India  much  refuse  fish  is  dried  on  the  beach, 


NITROGEN  GROUP  OF  FERTILIZERS         23 

and  then  sold  as  a  fertilizer.  Whilst  fish  guano  is  of  very 
varied  composition,  the  product  of  any  one  factory  is  often 
quite  constant.  The  average  of  a  large  number  of  samples 
obtained  from  North  Shields  has  been : — nitrogen  8*0  per 
cent.  ±0-2,  phosphoric  acid=5'9  per  cent.  ±O'8,  potash=n 
per  cent.  ±  0*3.  The  nitrogen  is  so  much  higher  in  amount 
and  fertilizing  value  than  the  other  ingredients  that  this 
fertilizer  may  be  looked  upon  as  belonging  to  the  organic 
nitrogen  group.  I,ike  all  the  members  of  this  group,  fish 
guano  is  much  slower  in  its  action  than  sulphate  of  ammonia 
or  nitrate  of  soda.  Its  decomposition  in  the  soil  depends 
upon  living  things,  from  bacteria  upwards.  Moisture, 
warmth,  and  lime  in  the  soil  greatly  facilitate  its  action. 
In  addition  to  its  purely  .chemical  value  the  physical  properties 
must  be  considered  (see  p.  68). 

An  objection  to  fish  meal,  not  uncommon  to  the  whole 
of  this  group,  is  that  it  is  sometimes  too  attractive  to  birds, 
or  even  four-footed  beasts.  Crows  have  been  known  to 
pull  it  out  of  the  soil  almost  as  fast  as  the  farmer  had  put 
it  in,  and  in  India  it  has  sometimes  induced  the  wild  pig 
to  root  it  out  and  trample  the  field.  For  cold  situations, 
or  for  late  application,  or  for  top  dressing  this  manure  is 
inferior  to  sulphate  of  ammonia  or  nitrate  of  soda. 

Dried  Blood. — Dried  blood  is  generally  only  the  clot, 
and  not  the  entire  blood,  as  the  boiling  down  of  big  quantities 
of  blood  is  a  difficult  problem.  Fresh  blood,  when  obtain- 
able, can  of  course  be  used  also.  Blood  decomposes  in  the 
soil  with  great  rapidity.  Dried  blood,  as  a  rule,  contains 
from  9  to  12  per  cent,  nitrogen. 

Hoofs  and  Horns. — These  are  the  product  of  the 
slaughter-house,  and  are  much  used  by  the  manufacturers 
of  artificial  manures.  They  contain  from  12  to  16  per  cent. 
of  nitrogen.  The  raw  horn  swells  very  slowly  in  the  soil, 
and  acts  slowly,  but  if  horn  be  steamed  it  swells  up  quickly 
in  moist  soil,  and  produces  a  moderately  quick- acting  fertilizer. 
This  material  must,  in  any  case,  be  very  finely  ground. 

Wool  Waste,  Shoddy,  Feather  Waste,  Feather  Dust, 
and  Silk  Waste,  are  all  waste  products  of  a  fibrous  and 


24  PLANT  PRODUCTS 

bulky  character.  They  are  much  appreciated  by  the  Kentish 
hopfarmers,  and  are  particularly  adapted  for  dry,  gravel, 
and  chalk  soils.  They  do  not,  however,  decompose  at  all 
readily  in  the  soil,  and  their  beneficial  action  is  probably 
quite  as  much  physical  as  chemical. 

Damaged  Cakes. — There  are  some  cakes  obtained  by 
pressing  oil  seeds  which  are  not  suited  for  cattle  feeding. 
To  animals  castor  cake  is  distinctly  poisonous  and  rape  cake 
is  very  bitter  and  distasteful.  Further,  some  meals  normally 
of  value  for  cattle  feeding  have  become  accidentally  damaged 
by  fire,  water,  or  mould.  All  of  these  materials  come  in 
usefully  as  fertilizers  for  the  soil.  Part  of  their  value  de- 
pends upon  secondary  effects,  independent  of  the  percentage 
of  nitrogen,  which  will  vary  from  4  to  7  per  cent.  Some  of 
the  least  edible,  such  as  castor  and  rape,  may  very  possibly 
injure  wire  worms  or  other  pests.  linseed  meal  (see  p.  136)  is 
stated  to  be  eaten  by  wireworms,  and  then  by  swelling 
inside  them  cause  them  to  die.  These  materials  decompose 
fairly  quickly  in  the  soil.  Mowha  cake  contains  saponin 
(see  p.  145),  and  is  used  to  remove  earthworms  from  golf 
greens. 

Meat  Meal  and  Refuse  from  Meat  Extract  Works. 
— These  contain  usually  about  5  to  8  per  cent,  nitrogen,  and 
10  to  15  per  cent,  phosphoric  acid.  Their  action  in  the  soil 
is  very  similar  to  fish  and  blood.  The  members  of  this  group 
of  fertilizers  stand  midway  in  their  action  between  "  Chemical 
Manures  "  and  farmyard  manure. 

REFERENCES  TO  SECTION  I 

Russell,  "  Artificial  Fertilisers,  Their  Present  Use  and  Future  Pros- 
pects," /.  Soc.  Chem.  Ind.,  1917,  p.  250. 

Hendrick,  "Field  Trials  with  Nitrogenous  Manuring,"/.  Soc.  Chem. 
Ind.,  1911,  523. 

Special  Leaflet  No.  57.     Board  of  Agriculture. 

Voelcker,  /.  Roy.  Agric.  Soc.  Eng.,  1904,  306 ;  1916,  244. 

Russell,  "  Manuring  for  Higher  Crop  Production,"  p.  7  (Camb.  Univ. 
Press). 

Hobsbaum  and  Grigioni,  "  Production  of  Nitrate  of  Soda  in  Chile," 
/.  Soc.  Chem.  Ind.,  1917,  p.  52. 

Kilburn  Scott,  "  Production  of  Nitrates  from  Air,  with  special  reference 
to  a  New  Electric  Furnace,"  /.  Soc.  Chem.  Ind.,  1915,  p.  113.  "The 
Manufacture  of  Nitrate  of  Ammonia,"  Chem.  News,  1917,  p.  175. 

Lamb,  "The  Utilization  of  Condemned  Army  Boots," /.  Soc.  Chem. 
Ind.,  1917,  p.  986. 


SECTION  II.— THE    PHOSPHORUS    GROUP 
OF    FERTILIZERS 

THE  phosphorus  group  of  fertilizers  consists  chiefly  of 
the  following  compounds  : — Mono-calcium  phosphate, 
CaH4P2O8.H2O,  which  is  easily  soluble  in  water,  very 
deliquescent,  and  strongly  acid ;  di-calcium  phosphate, 
Ca2H2P2O84H2O,  which  is  slightly  soluble  in  water,  and 
is  practically  neutral  to  litmus  paper ;  tri-calcium  phos- 
phate, Ca3P2O8,  a  rather  indefinite  compound,  much  less 
soluble  in  water,  but  attacked  to  some  extent  by  carbonic 
acid ;  tetra-calcium  phosphate,  Ca4P2O9,  which  has  been 
found  in  basic  slag ;  apatite,  Ca5(PO4)3F,  which  is  very 
insoluble  in  water ;  and  some  complex  compounds,  which  are 
both  phosphate  and  silicate,  occurring  in  basic  slag.  As, 
with  one  exception,  these  materials  are  not  very  soluble  in 
water,  it  is  necessary  that  most  of  the  phosphatic  fertilizers 
should  be  very  finely  ground.  In  the  case  of  basic  slag  the 
commonly  recognized  standard  of  fineness  is  the  ability  to 
pass  a  sieve  containing  100  wires  to  the  linear  inch,  or  10,000 
meshes  per  square  inch.  This  sieve  is  often  used  for  other 
fertilizers  as  well.  Small  experiments  conducted  at  Cockle 
Park,  the  Northumberland  County  Council  experimental 
farm,  showed  that  this  degree  of  fineness  was  about  correct. 
Those  portions  of  phosphatic  manures  which  only  passed 
sieves  much  coarser  than  the  above  had  little  influence 
on  the  development  of  clover,  whilst  phosphatic  manures, 
which  were  so  finely  ground  that  they  could  pass  a  sieve  with 
200  wires  to  the  inch,  showed  no  appreciable  advantage  over 
the  standard.  Special  distributors  have  been  constructed 
to  assist  in  spreading  these  manures  over  the  land  in  an  even 


26 


PLANT  PRODUCTS 


manner.  Broadcasting  these  very  fine  powders  is  trouble- 
some in  windy  weather.  Whether  these  phosphatic  manures 
happen  to  be  soluble  in  water  or  not,  they  very  quickly 
become  insoluble  in  the  soil.  The  soluble  compounds  attack 
the  lime  and  ferric  hydrate  in  the  soil  and  form  compounds 
insoluble  in  water.  There  is,  therefore,  no  appreciable  loss 
to  phosphatic  fertilizers  through  drainage.  At  Rothamsted, 
all  the  phosphates  added  during  the  preceding  fifty-five 
years  is  accounted  for  in  Table  3  : — 

TABLE  3. 
Phosphorus  Balance  Sheet,  Hall  and  Amos. 


P2O5  Ib.  per  acre. 

Broadbalk  plots. 

Hoosfield  plots. 

5. 

7. 

2. 

4. 

Supplied  in  manure 
Removed  in  crop 

3960 
790 

3810 
137° 

3390 
I2OO 

3390 
1240 

Balance  expected  in  soil 
„        found  in  soil 

3170 
3000 

2440 
2470 

2190 
2315 

2150 
2000 

It  will  be  noticed  that  the  very  large  amount  expected  to 
be  left  in  the  soil,  estimating  the  difference  between  what  was 
supplied  and  what  was  found  in  the  crop,  was  almost  exactly 
equal  to  the  amount  actually  found  in  the  soil.  In  two  cases 
a  little  too  much,  and  in  two  cases  just  too  little,  quite  as 
close  an  agreement  as  one  could  possibly  expect.  These 
results,  however,  refer  to  a  soil  which,  whilst  very  typical, 
is  poorer  than  some  agricultural  soils.  From  soils  that  are 
very  rich  in  phosphates,  such  as  some  garden  soils,  drainage 
does  remove  appreciable  quantities  of  phosphate.  The 
phosphates  in  the  soil,  whether  natural  or  added  by  fertilizers, 
are  attacked  by  the  carbonic  acid  in  the  soil,  and  thereby 
rendered  slightly  soluble.  The  root  hairs  of  a  plant  are 
probably  permeable  to  such  a  solution  of  phosphates  in 
water  containing  carbonic  acid.  When  such  solutions  have 
entered  the  root,  the  acid  in  the  root  will  take  up  the  phos- 
phate itself,  and  leave  the  carbonic  acid  free.  The  carbonic 


THE  PHOSPHORUS   GROUP  OF  FERTILIZERS     27 

acid  then  diffuses  out  again  into  the  soil,  and  dissolves 
more  phosphate.  Carbonic  acid,  therefore,  acts  as  a  carrier, 
and  though  the  organic  acids  in  the  root  are  said  not  to 
pass  out  into  the  soil,  they  nevertheless  have  an  important 
relationship  to  the  solution  of  phosphates  in  the  soil.  The 
rate  at  which  carbonic  acid  can  be  regenerated  will  depend 
upon  the  amount  of  acid  in  the  root.  Phosphates  are 
especially  valuable  for  stimulating  root  development,  and 
it  is  probably  for  this  reason  that  they  are  so  important 
for  the  development  of  turnip  seed  in  its  early  stages. 
Phosphates  usually  tend  to  accelerate  the  process  of  ripening. 
Phosphates  are  also  very  important  in  assisting  nitrogen 
fixation  in  the  soil,  either  directly  by  bacteria  in  the  soil  or 
indirectly  by  encouraging  the  growth  of  leguminous  plants. 

Basic  Slag. — Basic  slag  is  a  by-product  of  the  steel 
industries.  The  phosphorus  contained  in  the  ores,  fuel,  and 
lime  accumulates  in  the  pig  iron,  and  is  then  transferred 
to  the  basic  slag.  The  basic  slag,  therefore,  represents 
a  phosphorus  concentrate,  and  may  contain  phosphorus 
equivalent  up  to  40  per  cent,  of  tri-calcium  phosphate.  In 
addition  to  the  phosphoric  acid,  basic  slag  also  contains 
a  total  amount  of  lime,  equivalent  to  about  40  per  cent., 
with  a  few  per  cents,  of  magnesia  and  manganese,  6  to  10 
per  cent,  of  iron,  traces  of  vanadium  and  sulphur. 

The  lime  is  very  largely  in  some  state  of  combination, 
and  the  amount  of  lime  that  can  be  extracted  by  such  a 
reagent  as  a  solution  of  cane  sugar  is  very  small.  Lime  is 
needed  by  soils,  as  is  explained  in  Part  II.,  Section  II.,  for 
several  different  purposes,  (i)  neutralizing  the  acid  of  most 
manures  (see  p.  87),  (2)  assisting  nitrification  (see  p.  86), 
(3)  checking  disease  (see  p.  73).  For  these  miscellaneous 
purposes  it  has  been  found  that  calcium  oxide,  calcium 
hydrate,  and  calcium  carbonate  are  approximately  equivalent, 
calcium  for  calcium.  The  more  basic  calcium  silicates  are 
easily  attacked  by  very  feeble  acids,  and  in  this  case  calcium 
silicate  is  almost  as  good  as  other  forms  of  lime.  Looked  at 
from  the  point  of  view  of  the  farmer,  to  whom  the  application 
of  lime  to  the  soil  is  a  well-known  process,  an  equivalent  to 


28  PLANT  PRODUCTS 

a  dressing  of  lime  may  be  provided  by  any  of  the  forms  of 
lime  mentioned  above.  To  endeavour  to  represent  in  some 
way  the  value  of  basic  slag  for  replacing  lime  a  conventional 
calculation  is  adopted.  As  a  means  of  obtaining  information 
of  degrees  of  solubility,  citric  acid  is  commonly  taken  as 
a  convenient  standard,  but  there  is  no  real  theoretical  reason 
why  citric  acid  should  be  preferred  to  any  other  acid,  though 
it  is  certainly  convenient,  and  has  amply  justified  itself  in 
practice.  In  the  case  of  basic  slag  it  has  become  a  recognized 
standard  to  extract  the  slag  by  shaking  for  half  an  hour 
with  2  per  cent,  citric  acid  solution,  and  to  consider  that  the 
portion  dissolved  has  a  special  value  to  the  plant.  If  we  take 
the  lime  that  has  been  dissolved  by  citric  acid,  and  deduct 
from  that  the  lime  equivalent  of  the  phosphoric  acid  also 
dissolved,  we  shall  obtain  the  lime  soluble  in  citric  acid, 
over  and  above  what  may  be  regarded  as  neutralized  by  the 
phosphoric  acid.  This  figure  is  generally  known  as  the 
available  lime  in  the  slag,  and  may  fairly  represent  the  relative 
ability  of  the  slag  to  replace  the  ordinary  operation  of  liming 
the  soil.  It  is,  df  course,  purely  conventional.  There  is 
a  good  deal  of  evidence  to  show  that  the  citric-acid  soluble 
phosphate  in  a  slag  has  a  distinct  value  in  pot  experiments, 
and  in  all  cases  where  the  crop  has  only  a  short  period  of 
growth.  There  is  also  plenty  of  evidence  to  show  that  in 
the  case  of  pasture  such  solubility  is  of  little  advantage. 
Citric  solubility  must,  therefore,  be  regarded  as  a  test 
of  distinct  value,  in  its  proper  place,  but  its  importance  can 
easily  be  exaggerated.  The  degree  of  fineness  to  which 
basic  slag  has  been  ground  is  also  a  very  important  point. 
The  basic  slag  must  be  distributed  much  more  completely 
than  is  necessary  for  a  manure  soluble  in  water,  and  this 
can  only  be  achieved  if  the  material  is  very  finely  divided 
(see  p.  6).  Basic  slag  must  be  put  on  early  to  get  a  full 
value.  Probably  the  maximum  result  is  obtainable  about 
two  years  after  application,  but  with  slags  of  high  citric 
solubility  the  maximum  may  be  reached  earlier.  Soils 
containing  much  humus  or  peaty  material  are  especially 
benefited  by  slag.  To  what  extent  this  benefit  is  attributable 


THE  PHOSPHORUS   GROUP  OF  FERTILIZERS     29 

to  other  constituents  than  the  phosphorus  is  not  really  known. 
With  a  slow-acting  fertilizer  of  this  nature,  which  is  a  power- 
ful root  stimulant,  a  very  considerable  portion  of  the  observed 
benefits  may  be  quite  secondary  in  their  origin.  The  extra- 
ordinary change  in  the  physical  condition  of  a  soil  to  which 
basic  slag  has  been  regularly  applied  must  be  seen  before 
it  can  be  believed,  much  less  realized  and  appreciated.  At 
Cockle  Park,  where  this  manure  has  been  applied  for  many 
years  on  pasture,  the  final  improvement  of  the  soil  has  not 
yet  been  reached.  Between  1897  and  I91^  the  result  on 
the  physical  condition  of  the  soil  is  shown  by  comparing  a 
plot  that  has  had  no  manure  with  a  plot  which  has  basic  slag 
at  intervals  of  about  once  in  four  years.  The  plot  that  has 
received  no  basic  slag  showed,  on  careful  examination,  in 
1916,  no  appreciable  true  soil  at  all.  There  was  practically 
sub-soil  up  to  the  surface.  On  the  other  hand,  the  plot  which 
had  received  frequent  applications  of  basic  slag  now  has 
ten  or  twelve  inches  depth  of  a  good  loam,  and  is  apparently 
still  increasing  in  depth,  at  probably  a  rate  of  about  half 
an  inch  per  annum.  Such  a  profound  change  from  a  clay 
to  a  fibrous  loam  would  of  course  explain  any  result,  and  it 
is,  therefore,  quite  impossible  to  attempt  to  distinguish 
between  the  direct  results  of  the  addition  of  so  much 
phosphorus  and  the  indirect  results  which  have  benefited 
the  plant  by  roundabout  processes,  which  have  certainty  all 
originated  in  the  application  of  the  slag.  As  lime,  by  itself, 
has,  on  other  plots,  achieved  but  little  result,  one  can  only 
conclude  that  the  phosphorus  is  the  ultimate  origin  of  the 
observed  fertility.  Basic  slag  must  be  regarded  as  one  of  the 
more  lasting  manures,  but  it  appears  to  become  exhausted 
in  time,  and,  generally  speaking,  an  application  once  in 
four  years  will .  be  necessary.  The  soils  most  suited  are 
undoubtedly  heavy  clays  and  soils  of  a  peaty  character, 
whilst  a  sandy  soil  does  not  show  such  satisfactory  results, 
unless  it  is  manured  at  the  same  time  with  one  of  the 
potassium  group  of  fertilizers  (see  p.  40).  Basic  slag  has 
even  been  used  with  great  success  on  very  poor  pastures 
on  chalk,  and  seems  to  be  one  of  the  most  generally  useful 


30  PLANT  PRODUCTS 

of  all  the  fertilizers.  There  are  a  considerable  number  of 
slags  of  low  phosphorus  content,  and  it  is  one  of  the  most 
important  problems  before  us  to  utilize  these  materials. 
In  addition  to  basic  slag  there  are  acid  slags  produced  in  the 
steel  industry  which  do  not  contain  phosphorus.  When 
they  possess  any  value  for  applying  to  the  soil  it  is  probably 
due  either  to  their  lime  content,  or  to  the  mere  mechanical 
action  of  coarse  material. 

Mineral  Phosphates. — Deposits  of  mineral  phosphates 
are  to  be  found  in  many  parts  of  the  world ;  indeed,  on 
looking  at  the  parts  of  the  world  where  they  have  been 
found  one  cannot  resist  the  conviction  that  they  have  been 
found  just  where  they  have  been  most  looked  for,  and  that 
probably  more  extensive  search  will  discover  a  great  many 
new  deposits.  The  historical  "  Cambridge  Copr elites  "  have 
long  since  been  worked  out,  and  it  is  chiefly  to  foreign 
sources  that  we  now  look.  Of  these  the  Florida  phosphates 
may  be  regarded  as  of  the  highest  quality,  containing  about 
75  to  80  per  cent,  of  tri-calcium  phosphate.  North  Africa 
and  the  Pacific  Islands  provide  us  with  some  materials  of 
slightly  lower  grade,  whilst  Australasia  possesses  some  valuable 
deposits.  These  materials,  if  finely  ground,  can  be  applied 
directly  to  the  land.  They  are,  however,  much  less  soluble 
than  basic  slag,  and  for  direct  application  to  the  land  it 
certainly  seems  a  little  contradictory  for  England  to  export 
basic  slag  and  to  import  mineral  phosphates.  Where 
mineral  phosphates  have  been  systematically  applied  to 
pasture,  in  comparison  with  basic  slag,  some  quite  good 
results  have  been  obtained.  Satisfactory  results  have  also 
been  found  when  mineral  phosphates  have  been  used  with 
the  turnip  crop.  Nearly  all  the  mineral  phosphates  actually 
mined  are  used  for  the  manufacture  of  super-phosphate. 
The  manufacture  of  this  is  described  in  other  volumes  of  this 
series,  and  need  only  here  be  briefly  alluded  to. 

The  mineral  phosphate,  having  been  finely  ground,  is 
treated  with  sulphuric  acid,  and  is  run  into  a  "  den," 
where  the  reaction  is  completed.  As  the  resulting  material 
is  apt  to  be  sticky,  it  is  sometimes,  after  breaking  up,  dusted 


THE  PHOSPHORUS  GROUP  OF  FERTILIZERS     31 

over  with  dry,  finely  powdered  mineral  phosphate,  which 
prevents  the  sticky  grains  from  cohering.  At  some  works 
the  super-phosphate  is  dried  and  heated.  In  any  case, 
it  is  extremely  important  to  produce  a  fine,  dry  powder, 
which  neither  sticks  to  the  hand  in  broadcasting,  nor  clogs 
the  drill  in  machine  application.  Super-phosphate  should 
always  be  kept  in  a  dry  situation,  otherwise  the  skill  and 
labour  of  the  manufacturer  will  be  wasted  (see  p.  6). 

Super-phosphate,  when  stored,  is  apt  to  undergo  a  process 
known  as  reversion,  by  which  some  of  the  soluble  phosphate 
once  again  becomes  insoluble.  The  modern  improvements 
in  manufacture  have  reduced  the  risk  of  depreciation  in 
value  due  to  reversion  during  storage.  Directly  the  super- 
phosphate is  applied  to  the  land,  reversion  on  a  big  scale 
takes  place.  If  the  soil  is  tolerably  well  supplied  with  lime, 
the  mono-calcium  phosphate  will  become  converted  into 
di-  or  tri-calcium  phosphate.  When,  however,  the  soil  does 
not  contain  very  much  lime,  but  is  rich  in  iron,  much  of 
the  soluble  phosphate  will  become  ferric  phosphate.  The 
former  course  of  events  is  very  much  preferable. 

For  the  purpose  of  examining  super-phosphate  it  is 
common  to  take  a  portion  that  is  soluble  in  water  for  the 
estimation  of  phosphoric  acid.  In  the  United  States  of 
America  it  is  also  common  to  determine  the  amount  that 
dissolves  in  ammonium  citrate.  The  difference  of  the  two 
standards  is  not,  in  modern  products,  a  great  one.  The 
phosphate  applied  as  super-phosphate  will  not  penetrate  any 
depth  in  an  ordinary  soil  beyond  about  six  or  eight  inches. 
Super  -  phosphate  is  of  especial  value  as  a  quick-acting 
phosphatic  manure,  and  can  be  used  even  as  a  top  dressing. 
As  many  soils  are  deficient  in  phosphates,  super-phosphate 
is  often  one  of  the  fertilizers  which  produce  the  most  striking 
and  obvious  results. 

A  particular  type  of  fertilizer  which  has  proved  useful 
is  called  basic  super-phosphate.  This  consists  of  a  mixture 
of  super-phosphate  and  lime.  By  these  means  the  super- 
phosphate is  turned  into  phosphate  insoluble  in  water,  but 
very  easily  soluble  in  the  very  weakest  of  acids.  (See  Hughes, 


32  PLANT  PRODUCTS 

Bibliography.)  It  has  the  advantage  over  super-phosphate 
that  it  is  not  acid  in  character,  and,  therefore,  does  not 
encourage  the  development  of  "  Finger  and  Toe  "  disease  in 
turnips.  Its  extreme  solubility  in  very  feeble  acids  makes 
it  practically  as  available  to  the  plant  as  super-phosphate. 
It  is  also  very  dry  and  fine,  and  easily  distributed.  A  some- 
what similar  material  called  precipitated  bone  phosphate 
is  obtained  as  a  by-product  of  the  glue  and  gelatine  manu- 
facture. (See  Bennett.)  When  bones  are  treated  with  cold 
dilute  hydrochloric  acid,  the  framework  of  the  bone  is  left 
in  gelatine  and  the  calcium  phosphate  dissolved  by  the  acid. 
The  acid  liquids,  together  with  the  washings,  are  then 
precipitated  with  just  enough  lime  to  recover  all  the  phos- 
phoric acid,  giving  a  precipitate  about  half  di-calcium 
phosphate  and  half  tri-calcium  phosphate.  The  two  last- 
named  fertilizers  are  favourites  with  those  who  grow  turnips 
on  a  large  scale. 

Bone  Black  and  Bone  Ash. — In  sugar  refineries  con- 
siderable quantities  of  bone  black  were  used.  After  a  time 
it  is  beyond  the  power  of  the  users  to  regenerate  the  bone 
black  for  their  purpose,  and  this  is  then  sold  as  a  fertilizer. 
Bone  ash,  made  either  by  burning  bones  or  by  burning  the 
refuse  from  the  sugar  refineries  alluded  to  above,  or  obtained 
direct  from  South  America,  is  used  for  fertilizing  purposes. 
The  difference  between  used-up  bone  black  and  bone  ash 
is,  from  a  fertilizer  point  of  view,  of  no  particular  importance, 
since  a  few  per  cents,  more  or  less  of  carbon  will  not  influence 
the  results.  Bone  ash  is  fairly  readily  available  in  the  soil, 
and  in  this  respect  resembles  basic  slag.  It  is,  of  course, 
a  purely  phosphatic  manure,  and  may  contain  anything 
up  to  85  per  cent,  of  tri-calcium  phosphate.  It  is  quite 
suitable  for  any  of  the  purposes  of  precipitated  phosphate 
or  basic  super-phosphate,  but  cannot  be  used  as  a  top 
dressing  like  super-phosphate.  Bone  ash,  when  finely  ground, 
is  almost  entirely  soluble  in  weak  citric  acid. 

Fertilizers  containing  both  Nitrogen  and  Phosphorus. 
— The  different  requirements  of  crops  and  soils  preclude 
the  possibility  of  any  fixed  ratio  between  nitrogen  and 


THE  PHOSPHORUS   GROUP  OF  FERTILIZERS     33 

phosphorus  in  fertilizers,  but  for  most  arable  purposes  both 
will  be  required.     Probably  fertilizers  containing  two  ingre- 
dients are  often  sources  of  loss,  since  one  of  the  ingredients  is 
likely  to  be  in  excess.     This  loss  can  only  be  avoided  if  very 
careful  study  is  made  of  the  conditions,  and  the  ratio  of  nitro- 
gen to  phosphorus  adjusted  to  suit  the  special  requirements. 
Bones. — Bones  became  very  popular  as  soon  as  the  early 
ideas  of  phosphatic  manure  became  at  all  widespread.    The 
bones  of  animals  invariably  contain  some  grease.   The  amount 
of  grease  varies  with  the  bone,  but  on  the  general  average  a 
raw  bone  or  rag  bone  contains  about  12  per  cent,  water,  28  per 
cent,  nitrogenous  organic  matter,  10  per  cent,  fat,  44  per  cent, 
tri-calcium  phosphate,  and  5  per  cent,  calcium  carbonate. 
There  are  also  traces  of  magnesia  and  fluorine.     I^arge  bones 
of  such  a  composition  are  very  slow  in  decomposing  in  the 
soil,  and  may  be  regarded  as  having  no  practical  value. 
If  they  are  finely  ground  their  value  is  greatly  increased,  but 
the  fat  content  acts  as  a  preservative  and  diminishes  the 
value.     Fortunately,  the  fat  can  be  made  a  better  use  of. 
Under  the  best  systems  the  rag  bones  are  extracted  with 
petroleum  spirit,   and  the  grease  obtained  is  a  valuable 
product.     The   extraction   of   the   fat   renders   the    bones 
porous,  easy  to  grind,  and  available  after  application  to 
the  soil.     The  high-class  bone  meal  obtained  in  this  way 
will  often  have  over  5  per  cent,  of  nitrogen,  and  about  40 
per  cent,  to  45  per  cent,  of  tri-calcium  phosphate.     In  some 
works,  however,  the  fat  is  removed  by  a  process  of  steaming 
and  boiling,  which  removes  a  good  deal  of  gelatine  as  well 
as  fat.    The  remaining  bones  from  this  process  are  very 
porous,  grind  very  easily,  and  are  far  more  readily  available 
to  plants.    According  to  the  degree  of  treatment  the  bones 
have  received,  the  composition  will  vary  from  3  per  cent, 
nitrogen  and  50  per  cent,  tri-calcium  phosphate  to  i  per 
cent,  nitrogen  and  60  per  cent,  tri-calcium  phosphate.     The 
term    "  bone    meal "    is    commonly   understood   to    mean 
materials  containing  4  or  5  per  cent,  nitrogen,  which  have 
been  obtained  by  some  petroleum  extraction ;  whilst  the  term 
"  bone  flour  "  is  commonly  understood  to  mean  the  materials 
D.  3 


34  PLANT  PRODUCTS 

containing  from  i  to  3  per  cent,  of  nitrogen,  obtained  by  some 
boiling  or  steaming  process.  When  finely  divided,  these 
bone  fertilizers  are  readily  available  in  the  soil,  and  may  be 
considered  as  more  or  less  equivalent  to  basic  slag,  but  of 
course  the  nitrogen  is  in  addition.  The  small  amount  of 
calcium  carbonate  present  in  the  bones  is  also  useful  to  the 
soil.  lyike  all  other  manures  containing  organic  matter  bones 
will  provide  some  food  for  bacteria  or  other  forms  of  soil  life. 

Bones  are  also  treated  with  sulphuric  acid  in  the  same 
way  as  mineral  phosphates  are  treated  for  the  production 
of  super-phosphates.  The  product  is  generally  known  as 
dissolved  bones  or  vitriolated  bones.  For  the  manufacture 
of  this  article  rather  stronger  acid  is  necessary,  and  it  is 
not  practicable  to  get  the  whole  of  the  phosphate  into 
solution.  The  general  run  of  dissolved  bones  contain  about 
3  per  cent,  of  nitrogen,  15  per  cent,  of  phosphates  which  have 
been  rendered  soluble,  and  15  per  cent,  of  phosphates  which 
have  not  been  acted  on  by  the  acid  at  all.  By  these  means 
the  nitrogenous  matter  is  dissolved  as  well  as  the  phosphatic 
material,  so  that  the  resulting  dissolved  bones  must  be  looked 
upon  as  a  mixture  of  four  fertilizing  ingredients,  namely, 
soluble  phosphates,  insoluble  phosphates,  soluble  nitrogen, 
and  insoluble  nitrogen.  The  advantage  of  having  two 
degrees  of  solubility  is  very  marked :  the  insoluble  phosphates 
will,  on  application  to  the  soil,  remain  on  the  surface,  and 
the  soluble  will  penetrate  to  a  depth  of  a  few  inches.  In- 
soluble nitrogen  may  be  left  on  the  surface,  but  the  soluble 
nitrogen  in  this  case  will  penetrate  probably  to  a  foot  in 
the  soil,  since  those  portions  which  are  in  the  form  of  amino- 
acids  will  not  be  at  all  readily  fixed  by  the  soil,  but  will 
penetrate  to  a  greater  depth  than  ammonia  salts  could 
(see  pp.  7  and  13).  As  such  materials  will  be  very  mixed 
the  nitrogen  will  be  distributed  over  a  considerable  range 
and  depth  of  soil,  and  will  therefore  suit  a  variety  of  crops 
in  very  varied  stages  of  growth. 

A  very  frequent  type  of  bone  manure  is  composed  of 
super-phosphate,  bone  flour,  and  sulphate  of  ammonia. 
Here  again  there  is  the  advantage  of  two  kinds  of  phosphorus 


THE  PHOSPHORUS   GROUP  OF  FERTILIZERS    35 

and  two  kinds  of  nitrogen.  For  the  early  growth  of  practically 
all  crops  a  rich  surface  is  necessary.  When,  however,  the 
plants  have  grown  it  is  desirable  that  the  fertilizing  ingredients 
should  be  deeper  in  the  soil,  to  prevent  an  excessive  develop- 
ment of  surface  root,  with  the  subsequent  susceptibility 
to  drought. 

Guano. — This  old-established  and  favourite  type  of 
manure  is  produced  on  rocky  situations  with  little  rainfall, 
from  the  accumulations  left  by  sea-birds  during  the  nesting 
season.  Where  the  rainfall  is  very  scanty  the  amount  of 
nitrogen  in  the  guano  may  be  as  high  as  n  per  cent.  Where 
the  rainfall  is  considerable  the  nitrogen  may  be  removed  by 
washing  till  it  falls  to  i  per  cent.  In  guano  produced  under 
dry  conditions  the  phosphoric  acid  is  partially  soluble  in 
water ;  but  in  that  produced  in  wet  situations  the  constituents 
are  all  insoluble.  A  small  quantity  of  potash  is  often 
present,  say  i  per  cent.  The  varieties  of  guano  may  be 
divided  into  those  whose  value  is  chiefly  due  to  the  nitrogen 
and  those  whose  value  is  chiefly  due  to  the  phosphorus. 
The  phosphatic  kinds  will  barely  differ  in  their  properties 
from  bone  flour.  Those  of  the  nitrogenous  kind  will  be  of 
a  more  complex  character,  containing  both  nitrogen  and 
phosphorus  in  various  degrees  of  solubility.  Some  of  the 
less  valuable  guanos  are  treated  with  sulphuric  acid  to  render 
them  more  soluble. 

A  great  variety  of  artificial  mixtures  are  put  upon  the 
market  to  supply  both  nitrogen  and  phosphorus.  As  a 
rule  the  basis  of  these  is  super-phosphate,  to  which  has  been 
added  some  bone,  an}7  of  the  nitrogenous  organic  manures 
described  above,  and  not  infrequently  a  miscellaneous 
collection  of  materials  of  lower  value.  Some  materials,  in 
themselves  almost  worthless,  can  be  so  treated  as  to  bring 
them  into  use  for  this  group.  For  example,  leather  in  itself 
is  of  little  manurial  value,  but  it  can  be  treated  with  sulphuric 
acid  and  thereby  dissolved.  The  acid  is  not  lost  in  the 
process,  but  is  still  capable  of  dissolving  mineral  phosphates. 
Such  a  mixture  will  contain  the  leather  in  a  digested  form, 
as  well  as  soluble  and  insoluble  phosphate. 


36  PLANT  PRODUCTS 

Such  mixtures  as  are  here  being  described  are  very  rarely 
suitable  for  top  dressing.  They  are  best,  therefore,  applied 
in  the  drill  either  with  or  without  farmyard  manure. 
Containing  a  variety  of  ingredients,  they  are  in  many  respects 
safer,  since  even  if  the  user  possesses  the  knowledge  to  apply 
crude  fertilizers,  he  still  is  at  the  mercy  of  the  weather, 
and  it  is  not  possible  to  predict  exactly  which  of  the  crude 
fertilizers  would  be  the  best  to  apply.  A  mixture  which 
contains  a  variety  is  much  more  likely  to  apply  at  least 
something  that  is  necessary  (see  Introduction) . 

REFERENCES  TO  SECTION  II 

Collins  and  Hall,  "  The  Inter-relationships  between  the  Constituents 
of  Basic  Slag,"  Journ.  Soc.  Chem.  Ind.,  1915,  p.  526. 

Robertson,  "  The  Influence  of  Fluorspar  on  the  Solubility  of  Basic 
Slag  in  Citric  Acid,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  216. 

Bernard  Dyer,  "  Available  Mineral  Plant  Food,"  Journ.  Chem.  Soc., 
1894,  p.  115. 

Hughes,  Journ.  Soc.  Chem.  Ind.,  1901,  p.  325. 

Robertson,  "  Notes  on  the  Nature  of  the  Phosphates  contained  in 
Mineral  Phosphates,"  Journ.  Agric.  Science,  8,  p.  17. 

Robertson,  "  Solubility  of  Mineral  Phosphates  in  Citric  Acid,"  Journ. 
Soc.  Chem.  Ind.,  1916,  p.  217. 

Bennett,  "Animal  Proteids." 

Jones,  "The  Wagner  Test  as  a  Measure  of  the  Availability  of  the 
Phosphate  in  Basic  Slag,"  Journ.  Board  Agric.,  1914-15,  p.  201. 

Davis,  "The  Phosphate  Depletion  of  Soils  of  Bihar,"  Agric.  Journ. 
Ind.,  1917,  p.  181. 

Jatindra  Nath  Sen,  "  The  Influence  of  the  Presence  of  Calcium 
Carbonate  on  the  Determination  of  Available  Phosphoric  Acid  in  Soils  by 
Dyer's  Method,"  Agric.  Journ.  Ind.,  1917,  p.  258. 


SECTION  III.— THE   POTASSIUM  GROUP   OF 
FERTILIZERS 

FOR  some  years  past  the  German  potash  manures  have  com- 
pletely eclipsed  other  sources  of  potash,  and  it  is  only  since 
the  war  that  non-German  sources  have  once  again  come  into 
prominence.  There  is  little  doubt  that  the  German  potash 
manures  originated  in  the  same  way  as  most  salt  deposits, 
that  is  to  say,  sea  water  has  been  naturally  evaporated, 
producing  sodium  chloride,  then  complex  salts  of  magnesium 
and  potassium  sulphates  or  chlorides,  together  with  a  deposit 
of  calcium  sulphates.  The  material  put  upon  the  market 
as  kainit  has,  for  a  long  time,  had  little  connection  with  the 
mineral  properly  so  named,  but  has  simply  been  a  blend 
graded  to  12^  per  cent,  pure  potash  (K2O),  the  remainder  of 
the  material  being  chiefly  sodium  chloride,  with  some  mag- 
nesium sulphate.  The  composition  of  the  German  kainit 
manure  has  been  very  constant,  the  average  over  many  years 
past  having  been  12^50  ±  0*38  per  cent.  K2O  for  any  single 
sample.  Other  important  potash  manures  of  German  origin 
have  been  the  sulphate  and  the  muriate  (chloride).  The 
better  qualities  of  these  have  been  about  90  per  cent,  purhvy, 
but  lower  grades  have  also  been  on  the  market.  They  have 
always  been  sold  under  guarantee. 

A  very  old  type  of  potash  manure  is  wood  ash.  The 
ashes  of  full-grown  timber  do  not  contain  much  potash,  but 
the  ashes  of  small  twigs  are  fairly  rich.  The  table  on 
p.  38  will  roughly  show  the  amount  of  potash  in  many 
types  of  wood  ashes. 

The  ashes  of  coal  contain  hardly  any  potash,  but  certain 
particular  wind-blown  coal  ashes  in  industrial  concerns 
contain  appreciable  quantities  of  potash.  The  dust  deposited 


PLANT  PRODUCTS 

TABLE  4. — WOOD  ASHES. 


K20 

CaO 

Pao6 

Si02 

Beech  trunk  .  . 

per  cent. 
16 

per  cent. 
56 

per  cent. 
6 

per  cent. 
6 

Beech  branch 

14 

48 

12 

i 

Birch  .. 

12 

58 

8 

4 

Oak 

10 

72 

6 

2 

Larch 

15 

26 

4 

4 

Scotch  pine    .  . 

12 

50 

8 

15 

If  in  the  Table  4  the  figures  represent  pounds,  it  would  take  4^  tons 
of  beechwood  or  8J  tons  Scotch  pine  to  be  burnt  for  their  production. 

in  flues  of  blast-furnaces  and  boilers  often  contains  a  con- 
centration of  certain  ingredients  which  may  raise  the  potash 
in  the  dust  to  5  or  10  per  cent.  The  vast  majority  of  these 
materials  are,  however,  very  disappointing,  and  rarely 
repay  transport,  although  by  evaporation  of  an  aqueous 
extract  a  concentrate  may  be  obtained.  A  useful  waste 
product  is  obtained  in  the  case  hardening  of  steel,  during 
which  small  parts  of  machinery  are  heated,  then  plunged 
into  mixtures  some  of  which  contain  potassium  ferro- 
cyanide.  Although  this  material  when  used  for  case 
hardening  lasts  a  long  time,  when  worn  out  it  is  still  rich 
in  potassium,  and  may  even  contain  20  per  cent,  potash. 
The  cyanides  present  would  be  prejudicial  to  plant  life  if 
applied  after  the  plant  had  started  growth,  and  would  also 
tend  to  check  germination.  Similarly,  even  wood  ashes, 
being  strongly  alkaline,  should  be  allowed  some  time  to  work 
into  the  soil  before  the  seeds  are  sown. 

The  reactions  of  potassium  sulphate  with  the  soil  are 
very  similar  to  those  of  ammonium  sulphate.  The  potash 
combines  with  clay  and  humus,  and  the  sulphuric  acid  com- 
bines with  lime,  and  then  washes  out  of  the  soil.  Potassium 
chloride  reacts  similarly,  the  chlorine  taking  lime  and  washing 
out  of  the  soil.  When  crude  materials,  like  kainit,  are  applied 
to  the  soil  the  sodium  chloride  washes  out,  leaving  the  potash 
and  most  of  the  magnesia  behind.  These  manures  tend  to 
exhaust  the  soil  of  lime.  Wood  ashes,  however,  do  not  take 
away  lime  out  of  the  soil,  but  tend  to  make  it  alkaline  and 


THE  POTASSIUM  GROUP  OF  FERTILIZERS    39 

deflocculated,  and,  therefore,  to  interfere  with  bacteria 
or  plant  life.  Such  refuse  materials  as  contain  cyanides 
will  require  a  fairly  lengthy  period  to  enable  the  poisonous 
cyanogen  compounds  to  be  rendered  harmless  and  converted 
into  useful  nitrates.  It  may  be  taken  as  a  general  rule  that 
potash  manures  should  be  applied  early.  Potash  is  not 
fixed  in  the  soil  with  quite  the  same  completeness  as  phos- 
phate, but  in  a  parallel  calculation  to  that  given  in  the 
section  dealing  with  phosphatic  manures  it  has  been  found 
at  Rothamsted  that  something  like  about  three-quarters  of 
the  potash  can  be  accounted  for,  the  remainder  having 
presumably  been  lost  in  the  drainage  during  fifty  odd  years. 
The  need  for  potash  manures  is  not  as  great  as  for  phosphates 
or  nitrogen.  Cla}^  soils  contain  a  sufficient  amount  of  potash 
for  most  crops.  It  is  only  on  the  light  and  sandy  soils  that 
potash  manure  is  absolutely  essential.  The  really  most 
important  member  of  the  group  of  potassium  fertilizers  is, 
however,  farmyard  manure.  The  recent  effort  to  utilize 
blast  furnace  dust  promises  a  valuable  addition  to  home 
potash  production. 

REFERENCES  TO   SECTION   III 

Cresswell,  "  Possible  Sources  of  Potash,"  Journ.  Soc.  Chem.  Ind.,  April, 
*f9i5,  P-  387- 

Russell,  "  How  can  Crops  be  Grown  without  Potash  ?  "  Journ.  Board 
of  Agric.,  1915-16,  p.  393. 

Voelcker,  "  Absorption  of  Potash  by  Soils  of  known  Composition," 
Journ.  Roy.  Agric.  Soc.,  25,  n. 

Schreiner,  "  The  Absorption  of  Potassium  by  Soils,"  Journ.  Phys.  Chem., 
1906,  p.  361. 

Cranfield,  "A  New  Source  of  Potash,"  Journ.  Board  of  Agric.,  1917-18, 
p.  526. 


SECTION  IV.— MIXED    FERTILIZERS 

As  a  general  rule  both  crops  and  soils  will  demand  a 
mixture  of  the  crude  fertilizers,  and  there  are  many  occa- 
sions on  which  it  is  convenient  to  be  able  to  purchase 
ready-made  mixtures  of  these  crude  materials.  The  chief 
difficulty  that  occurs  in  the  application  of  crude  fertilizers 
is  in  their  even  distribution  over  the  land.  It  is,  there- 
fore, advantageous  to  obtain  a  material  which  is  not  too 
concentrated  in  any  one  ingredient.  Hence  there  is  a 
distinct  advantage  in  obtaining  several  materials  ready 
mixed.  As,  however,  the  requirements  of  soils  and  crops 
are  very  varied,  and  climatic  conditions  will  modify  the 
needs  of  any  particular  crop  or  soil,  it  becomes  practically 
impossible  to  design  a  mixture  for  any  large  group  of  districts, 
soils,  or  crops.  Certain  general  principles  are  quite  well 
established,  (i)  nitrogen  for  cereals,  phosphorus  for  roots, 
potassium  for  pulses,  and  (2)  phosphorus  for  heavy  soils, 
and  potassium  for  light  soils.  But  it  is  quite  impossible  to 
adhere  rigorously  to  any  such  system,  because  in  practice 
a  succession  of  crops  are  grown,  and  what  is  left  over  from 
one  crop  is  used  up  by  the  next.  Nevertheless,  there  is 
a  distinct  demand  for  specific  mixtures.  A  very  popular 
mixture  is  potassic  super-phosphate  blended  so  as  to  contain 
about  20  per  cent,  soluble  phosphate,  and  about  3  per  cent, 
potash.  Such  a  mixture  can  be  made  in  a  dry  form,  handier 
for  distribution  than  either  of  its  ingredients  alone.  Mixtures 
of  super-phosphate,  sulphate  of  ammonia,  and  potash  salts 
are  often  made  and  sold  under  specific  names,  such  as  "  Corn 
Manure/'  "Grass  Manure,"  or  "Turnip  Manure."  Too 
much  attention  should  not  be  given  to  the  name.  Estimates 
should  only  be  based  on  the  guaranteed  analysis.  Provided 


MIXED  FERTILIZERS  41 

the  guaranteed  analysis  and  the  price  correspond,  and 
granted  that  the  material  is  in  a  good,  convenient  condition 
for  sowing,  and  that  the  mixture  really  represents  what  the 
crop  on  that  particular  soil  and  under  that  particular  climate 
wants,  then  this  mixture  may  be  used  with  satisfaction. 
For  the  purpose  of  checking  the  prices  of  these  materials, 
a  unit  of  22*4  pounds  is  commonly  adopted.  For  Great 
Britain  these  unit  prices  are  published  in  the  Journal  of 
the  Board  of  Agriculture,  which  will  give  the  values  from 
time  to  time.  For  example,  in  the  number  for  April,  1917, 
one  may  see  that  in  London  the  unit  price  of  nitrogen  in  the 
form  of  sulphate  of  ammonia  was  155.  4%d.,  but  that  nitrogen 
in  other  forms  was  more  expensive,  and  that  at  all  the  other 
places  named  in  the  table  the  same  was  true.  Thus  with  any 
mixture  in  which  nitrogen  is  probably  derived  from  sulphate 
of  ammonia  it  would  be  not  unreasonable  to  take  this  figure. 
The  value  of  a  unit  of  soluble  phosphate  in  super-phosphate 
varies  according  to  place  from  35.  i\d.,  to  45.  8%d.,  and  for 
rough  purposes  one  may  call  it  45.  At  the  time  potash  is 
not  quoted,  but  before  the  war  potash  was  valued  at  35.  or 
45.  a  unit.  A  calculation  can  be  made  as  follows : — 

TABLE  5. — MANURE. 

£     s.     d. 

Nitrogen,  5  per  cent.,  at  155.    ..          ..  3     15    o 

Soluble  phosphate,  20  per  cent.,  at  45. 
Potash,  3  per  cent.,  at  105. 


Mixing,  bagging,  etc. 

Total  value 

If  less  than  5  tons,  add  5  per  cent. 
If  payment  delayed  till  harvest,  add  5  per  cent. 


4  o  o 
i  10  o 
o  15  o 


10  o  o 
o  10  o 
o  10  6 


£11 


Prices  will  vary  from  time  to  time,  but  are  published 
monthly  in  the  Journal  of  the  Board  of  Agriculture. 

It  is  not  difficult  to  make  one's  own  estimate  of  unit 
prices  for  one 's  own  special  conditions .  Sulphate  of  ammonia 
contains  so  nearly  20  per  cent,  of  nitrogen  that  the  unit  price 
of  nitrogen  in  sulphate  of  ammonia  is  almost  exactly  the 
same  in  shillings  as  the  price  is  in  pounds  per  ton,  that  is, 
when  sulphate  of  ammonia  costs  about  £16  per  ton  the  unit 


42  PLANT  PRODUCTS 

price  of  nitrogen  is  i6s.  If  super-phosphate,  with  30  per 
cent,  of  soluble  phosphate,  cost  about  £6  per  ton,  each  one 
per  cent,  will  cost  45.  It  will  be  noted,  in  comparing  the 
tables  of  the  Journal  of  the  Board  of  Agriculture,  that 
sometimes  special  forms  are  very  expensive ;  for  example, 
in  dissolved  bones  soluble  phosphate  is  much  more  expensive 
than  in  super-phosphate.  The  nitrogen  in  dissolved  bones 
is  assessed  at  a  high  rate,  as  it  is  also  in  the  case  of  nitrate 
of  soda,  but  all  these  conditions  are  quite  temporary,  and 
a  few  months  later  on  the  relative  prices  may  be  different. 

In  practice,  the  farmer  should  endeavour  to  discover 
for  himself,  by  experiments,  what  particular  mixture  suits 
his  soil  and  system  of  farming. 

Farmyard  Manure. — This  very  ancient  and  well- 
known  commodity  owes  its  value  partly  to  its  chemical, 
partly  to  its  physical,  and  partly  to  its  biological  effects . 
The  elementary  constituents  are  carbon,  hydrogen,  oxygen, 
and  nitrogen,  which  constitute  the  non-metallic  part ; 
potassium,  phosphorus,  calcium,  which  constitute  the  metallic 
part,  both  parts  being  of  value  ;  with  some  small  amounts 
of  aluminium,  iron,  and  silicon,  which  may  be  considered  as 
having  no  value.  These  materials  are  combined  together 
as  humus,  organic  fibre,  and  salts.  Water  is  present  to  the 
extent  of  from  60  per  cent,  to  80  per  cent.  Farmyard  manure 
is  by  no  means  a  dead  thing.  It  is  full  of  bacterial  life, 
which  has  a  strong  influence  on  its  value.  Considering,  first 
of  all,  the  forms  in  which  these  elements  of  value  occur,  we 
find  that  the  nitrogen  is  very  rarely  indeed  in  the  oxidized 
condition  of  a  nitrate.  Very  old  heaps  of  farmyard  manure, 
say  two  years  old,  certainly  do  contain  small  quantities  of 
nitrate,  but  this  age  is  not  usual  in  farm  practice.  An 
important  fraction  of  the  nitrogen  is  present  in  the  form 
of  ammonia,  which  chiefly  occurs  as  the  result  of  the 
decomposition  of  urea  CO(NH2)2.  Urea  is  fermented  by 
a  special  micro-coccus,  so  that  in  a  day  or  so  the  urea  has 
become  completely  converted  into  ammonium  carbonate.  The 
ultimate  result  of  this  change  is  represented  by  the  equation 
CO(NH2)2  +  2H2O=(NH4)2CO3.  The  ammonia  so  produced 


MIXED   FERTILIZERS  43 

will  very  likely  react  with  some  of  the  sulphates  present, 
so  that  in  the  manure  heap  the  ammonia  will  be  partly  as 
ammonium  sulphate.  In  addition  to  this,  as  the  organic 
matter  is  decomposed  by  bacterial  action,  a  portion  of  it  will 
form  those  vague  compounds  which  we  call  humic  acid, 
which  will  enter  into  combination  with  the  ammonia  and 
produce  the  soluble,  dark-brown  coloured  substance, 
ammonium  humate.  Some  nitrogen  is  also  present  in  the 
amide  form.  Urea  itself  is  an  amide,  but  is  not  the  only 
one  present.  Many  other  amides  are  produced  by  the 
action  of  bacteria  upon  proteins.  Amino-acids  and  peptones 
are  also  present.  A  fair  proportion  of  the  soluble  nitrogen 
which  exists  in  the  manure  heap  results  from  the  bacterial 
digestion  of  the  proteins.  Many  of  the  bacteria  in  the  manure 
heap  belong  to  the  class  that  liquefy  gelatine.  The  liquefac- 
tion of  gelatine  is  only  a  special,  easily  observed  case  of  the 
peptonization  of  proteins,  and  a  part  of  the  proteins  which 
have  not  been  digested  by  the  beasts  goes  into  the  peptone 
form  in  the  manure  heap.  Of  the  albuminoids  in  the  dung, 
some  are  soluble,  but  most  are  not  merely  insoluble  in 
water,  but  very  resistant  to  all  chemical  change ;  indeed  part 
of  the  proteins  that  are  passed  by  the  beasts  is  the  residuum 
of  dead  bacteria,  which  needs  protracted  decomposition. 

The  potassium  in  the  manure  heap  will  occur  as  potassium 
sulphate  and  potassium  humate.  Most  of  the  potassium  is 
soluble,  and  therefore  very  easily  lost,  unless  care  be  taken 
for  its  preservation. 

The  phosphorus  in  the  manure  heap  is  very  largely  in 
the  form  of  phosphates,  but  some  part  is  organic.  Although 
the  manure  heap  is  alkaline,  and  contains  lime  and  ferric 
hydrate  which  would  normally  precipitate  all  the  phosphates, 
yet  in  the  presence  of  so  much  soluble  organic  matter,  iron 
and  calcium  are  not  able  to  precipitate  phosphoric  acid  in 
alkaline  solution,  so  that,  as  a  rule,  at  least  one-half  of  the 
phosphorus  is  soluble. 

The  calcium  present  is  not  in  sufficient  quantities  to 
appreciably  affect  the  total  value  of  the  manure,  but  it  has 
some  action  upon  bacterial  life.  It  will  occur  mostly  in 


44  PLANT  PRODUCTS 

combination  with  humic  acid,  with  which  the  calcium  forms 
an  insoluble  compound,  but  some  soluble  substance,  like 
calcium  sulphate,  will  often  be  found  in  the  manure  heap. 

The  organic  materials  occur  chiefly  either  as  fibres  or 
as  gummy  matter.  The  fibrous  material  is  very  important 
in  enabling  the  manure  heap  to  retain  its  liquid  constituents, 
and  in  maintaining  the  open  structure  necessary  for  admission 
of  air  in  limited  amounts.  The  gummy  material  provides 
the  humic  acid  and  other  colloids,  which  will  fix  or  absorb 
the  substances  of  manurial  value.  The  water  present  plays 
a  large  part  in  the  decomposition  of  the  manure  heap  and 
is  chiefly  absorbed  by  the  litter.  The  bacteria  present  are 
mostly  such  common  forms  as  coli  communis  or  subtilis, 
the  former  derived  from  the  beasts  and  the  latter  from  the 
fodder. 

The  study  of  the  proximate  constituents  is  quite  as 
important  as  that  of  the  ultimate  constituents.  These 
consist  of  three  parts,  the  dung,  the  urine,  and  the  litter. 
The  dung  owes  its  chief  value  to  nitrogen  and  phosphorus. 
In  old  animals  it  is  richer  than  in  young  animals,  because  the 
young  animals  utilize  food  better.  In  the  case  of  the  grain- 
fed  horse  it  is  rich  and  decomposes  rapidly ;  but  in  the  case 
of  the  grass -fed  horse  it  is  poorer,  and  slower  in  action. 
Sheep  produce  the  richest  and  the  cow  produces  the  poorest. 
A  fat  bullock  will  produce  better  dung  than  a  cow,  and  the 
manure  will  decompose  much  quicker. 

The  urine  which  decomposes  very  rapidly  owes  its  chief 
value  to  nitrogen  and  potassium.  With  root-fed  beasts  it 
is  weak,  and  with  grain-fed  beasts  it  is  concentrated.  Much 
of  the  nitrogen  occurs  as  urea,  and  ferments  to  ammonium 
carbonate  within  two  or  three  days.  If  the  food  is  very 
coarse — that  is,  contains  much  straw  or  inferior  hay — as  much 
as  one-third  of  the  nitrogen  appears  in  the  form  of  hippuric 
acid  (benzamido  acetic  acid,  C6H5.CO.NH.CH2.CO.OH).  It 
will  be  noticed  at  once  that  nitrogen  for  nitrogen,  hippuric 
acid  contains  very  much  more  carbon  than  urea,  CO(NH2)2, 
and  its  excretion  involves  loss  of  food  and  loss  of  energy. 
When  foods  contain  a  big  proportion  of  pentosans  the  amount 


MIXED  FERTILIZERS  45 

of  hippuric  acid  secreted  is  much  greater.  Of  the  other 
constituents  of  the  urine  the  potassium  occurs  as  sulphate 
and  chloride,  whilst  sodium  occurs  as  sodium  chloride. 

The  litter  is  a  very  important  part  of  the  manure  heap. 
Unless  there  is  a  generous  supply  of  litter  the  beasts  will 
be  uncomfortable  and  the  valuable  portion  of  the  manure 
will  be  lost  by  drainage.  Most  of  the  potassium  and  half 
of  the  nitrogen  occur  in  soluble  form,  which  are  only  retained 
by  the  absorptive  capacity  of  the  litter.  The  litter  itself 
may  contain  some  nitrogen,  phosphorus,  and  potassium, 
but  its  chief  value  depends  upon  the  water-absorbing 
capacity.  One  part  of  leaves  will  absorb  about  two  parts, 
by  weight,  of  water  ;  straw  will  hold  three  parts  ;  sawdust 
four  parts  ;  tan  refuse  five  parts  ;  rough  peat  six  parts  ; 
and  picked  peat-moss  litter  about  ten  parts.  Some  very 
exceptional  peat-moss  litter  may  even  hold  eleven  or  twelve 
times  its  weight  of  water  without  drainage.  It  is  not  practic- 
able under  ordinary  conditions  to  get  such  good  results 
as  these,  because  the  trampling  of  the  beasts  will  compress 
the  litter,  and  squeeze  something  out,  but  the  relative  values 
of  the  materials  will  be  roughly  as  stated.  In  practice  much 
will  depend  upon  the  relative  cost  of  these  different  forms 
of  litter,  but  where  practicable  the  more  absorptive  kinds 
should  be  preferred,  because  it  will  save  so  much  labour  in 
handling  bulky  useless  material.  However  a  good  deal  of 
the  value  of  the  manure  depends  upon  its  physical  effect  in  the 
soil,  its  provision  of  food  for  soil  organisms,  and  its  production 
of  carbon  dioxide  in  the  soil.  It  is  not  possible  to  lay  down 
any  very  strict  rules  on  this  subject.  Straw  will  certainly 
provide  better  food  for  soil  organisms  than  most  of  the 
other  ingredients  named.  Sawdust  appears  to  encourage 
harmful  organisms  if  large  quantities  of  manure  are  used, 
if  it  is  badly  distributed  in  the  soil,  and  if  the  soil  is  wet 
and  compact .  Admission  of  air  to  the  soil  is  also  an  important 
point  in  the  value  of  farmyard  manure,  and  for  such  a  purpose 
peat-moss  litter  will  serve  much  better  than  any  other  member 
of  the  series.  It  must  also  not  be  forgotten  that  the  straw 
might  be  used  partly  for  feeding,  as  it  would  then  not  be 


46  PLANT  PRODUCTS 

necessary  to  use  so  much  straw  for  bedding.  A  very  common 
and  useful  solution  of  these  difficulties  is  to  use  both,  to 
put  peat  moss  litter  at  the  bottom  and  clean  straw  at  the 
top.  It  makes  a  very  comfortable  bed  for  the  beasts,  and 
the  liquor  is  well  absorbed  by  the  peat  moss  underneath. 
The  relative  absorptive  value  of  most  of  these  materials  is 
increased  by  fine  chopping,  and  unpromising  materials 
may  be  much  improved  by  being  passed  through  a  chaff 
cutter.  The  relative  absorptive  power  of  different  litters 
can  be  so  easily  determined  that  it  would  be  wise  for  users 
to  test  them  themselves.  All  that  is  necessary  is  some 
sort  of  scales  and  measuring  vessel.  A  very  convenient 
method  is  to  weigh  5  grammes  of  the  material,  add  100  cubic 
centimetres  of  water,  and  allow  to  soak  for  a  few  hours. 
The  remaining  mixture  is  then  poured  on  to  a  funnel,  which 
has  placed  in  it  a  small  filter  disc  or  even  a  common  marble. 
The  portion  of  liquor  drained  through  is  measured  in  the 
cylinder,  and  the  difference  from  what  was  originally  taken 
gives  the  portion  absorbed.  With  peat-moss  litter  it  will 
be  found  that  5  grammes  will  absorb  about  50  cubic  centi- 
metres, or  an  absorptive  capacity  of  10  per  unit. 

The  Manufacture  of  Farmyard  Manure.  — As  regards 
the  quantities  produced,  a  cow  will  give  about  45  pounds 
of  dung  every  day,  containing  about  8  pounds  of  dry  matter 
and  37  pounds  of  water.  In  the  average  of  all  animals  the 
organic  matter  in  the  dung  represents  43  per  cent,  of  the 
organic  matter  eaten,  and  the  nitrogen  yielded  is  20  to  40 
per  cent,  of  that  eaten.  This  wide  range  of  nitrogen  is  due 
to  the  great  variation  in  the  proportions  of  nitrogenous, 
matter  in  the  food.  The  phosphorus  in  the  dung  equals 
95  per  cent,  of  that  eaten,  and  the  potassium  about  16  per 
cent,  of  that  eaten. 

Urine. — The  cow  gives  about  50  pounds  a  day,  with 
4  pounds  of  dry  matter,  but  the  amount  is  very  subject  to 
variation,  according  to  the  type  of  feeding.  The  organic 
matter  equals  about  3  percent,  of  that  eaten, the  nitrogen  from 
60  to  80  per  cent,  of  that  eaten,  the  phosphorus  about  3  per 
cent,  of  that  eaten,  and  the  potassium  from  80  to  85  per  cent. 


MIXED  FERTILIZERS 


47 


of  that  eaten.  A  striking  point  is  the  great  difference 
between  the  mode  of  excretion  of  potassium  and  phosphorus 
— the  potassium  is  almost  entirely  in  the  liquid  portion, 
and  the  phosphorus  almost  entirely  in  the  solid  portion. 

Taking  the  whole  excreta  together,  the  organic  matter 
corresponds  to  46  per  cent,  of  that  eaten,  the  nitrogen  from 
70  to  95  per  cent,  of  that  eaten,  and  the  potassium  and 
phosphorus  from  95  to  98  per  cent,  of  that  eaten.  It  will 
be  noticed,  therefore,  that  very  little  phosphorus  and 
potassium  are  actually  removed  and  sold  off  the  farm  in 
the  form  of  meat.  The  loss  of  nitrogen  by  sale  from  the  farm 
is  slightly  greater,  but  under  conditions  of  feeding  livestock 
very  little  of  the  manurial  ingredients  are  sent  away,  and  the 
stock  in  hand  of  fertilizing  elements  is  always  very  large. 
The  possible  loss  by  drainage  of  the  nitrogen  can  be  made  up 
on  the  farm  itself  by  other  methods,  as  shown  in  Part  II., 
but  the  loss  of  potassium  salts  by  drainage  constitutes  a 
serious  diminution  in  fertility  of  the  soil.  It  can  only  be 
replaced  by  purchases  of  potassium  compounds.  In  India, 
and  other  countries  where  cattle  feeding  is  not  carried  out 
systematically,  but  where  bullocks  are  used  for  draft  purposes 
and  not  fattened  for  beef,  little  attention  is  paid  to  conserving 
the  manures  from  the  animals.  Very  often  the  cattle  dung 
is  not  used  as  manure  at  all,  but  is  used  as  fuel,  mixed  with 
straw,  or  as  a  material  for  plastering  walls,  etc.  Where  it 
is  used  as  a  manure  it  contains  no  litter  or  urine. 

TABLE  6. — MANURE  IN  INDIA. 


Cattle  dung. 
Grass  fed. 

Cattle  dung. 
Well  fed. 

Cattle  urine. 

Water 

75*o 

73*5 

93'° 

Organic  matter 

14*5 

iro 

3'5 

Nitrogen    .  . 

. 

0*27 

o'35 

0-56 

Phosphoric  acid 

. 

0-18 

0-14 

O'O2 

Potash 

. 

0-30 

0-18 

1-13 

Lime 

• 

0-28 

0-25 

0'12 

Passage  from  Food  to  Dung. — The  history  of  the 
nitrogen  that  is  consumed  by  the  live-stock  on  the  farm  is 
shown  in  the  following  table  : — 


48  PLANT  PRODUCTS 

TABLE  7. — NITROGEN  HISTORY  OF  FEEDING. 


] 

Excreta  %. 

As  carcase 

or  milk 
%. 

Solid. 

Liquid. 

Total. 

Horse  at  rest 

_ 

43 

57 

IOO 

Horse  at  work 

— 

29 

71 

IOO 

Fattening  ox 

4 

23 

73 

96 

Fattening  pig 

15 

21 

64 

85 

Fattening  sheep 

4 

I? 

79 

96 

Milking  cows 

25 

1  8 

57 

75 

Calf  on  milk 

69 

5 

26 

31 

Average  of  all 

17 

22 

61 

83 

Average  of  worldng  horse, 

ox  and  sheep 

3 

23 

74 

97 

From  which  it  \\  ill  be  seen  that  the  effect  of  working  a  horse 
is  to  increase  the  proportion  of  nitrogen  that  is  excreted  in 
the  liquid.  The  cow  gives  a  higher  proportion  of  nitrogen 
as  saleable  products,  and,  in  consequence,  leaves  less  for 
the  manure  heap.  A  calf  fed  on  milk  uses  up  most  of  the 
nitrogen  for  its  growth,  and  leaves  but  a  small  fraction  for 
manure.  The  average  stock  on  a  farm  will  vary  according 
to  the  system  of  management,  but  in  no  case  will  the  pro- 
portion of  nitrogen  sold  be  anything  but  small.  The  bulk 
of  the  nitrogen  that  is  eaten  in  the  food  goes  back  into  the 
manure,  mostly  in  the  soluble  form  and  liable  to  loss  by 
drainage.  The  farm  is,  therefore,  compelled  to  carry  a  very 
big  working  capital  in  the  form  of  nitrogen,  from  which  the 
annual  return  is  comparatively  small. 

A  parallel  table  can  be  worked  out  for  the  potassium  history. 

TABLE  8. — POTASSIUM  HISTORY  OF  FEEDING. 


Horse 

Fattening  ox 
Fattening  sheep 
Fattening  pig 
Milking  cow 


Excreta  %. 

As  carcase 

or  milk 

%. 

Solid. 

Liquid. 

Total. 

_ 

14 

86 

IOO 

I 

16 

83 

99 

I 

6 

93 

99 

2 

14 

84 

98 

10 

16 

74 

90 

MIXED  FERTILIZERS 


49 


It  will  be  seen  in  this  table  that,  excepting  in  the  one 
case  of  cows  giving  milk,  the  proportion  returned  as  saleable 
is  very  small  indeed.  Very  nearly  the  whole  of  the  potassium 
in  the  food  is  returned  to  the  manure  heap  in  a  liquid  form, 
easily  lost  by  drainage.  The  conservation  of  this  potassium 
is  a  very  important  problem,  since  where  there  are  clay  fields 
the  amount  of  potassium  in  the  soil  is  naturally  large,  but 
where  the  soil  is  sandy  the  potassium  is  needed  as  a  fertilizer. 

The  phosphorus  history  of  the  food  eaten  is  given  in 
Table  9,  from  which  it  will  be  seen  that  the  major  part  of 
the  phosphorus  eaten  is  returned  to  the  manure  heap  in 
the  solid  form,  and  is,  therefore,  not  easily  lost. 

TABLE  9. — PHOSPHORUS  HISTORY  OF  FEEDING. 


Excreta  %. 

As  carcase 

or  milk 

%. 

Solid. 

Liquid. 

Total. 

Horse 

__ 

99 

I 

100 

Ox 

14 

85 

I 

86 

Pig 

16 

68 

16 

84 

Sheep 

14 

83 

3 

86 

Cow 

23 

76 

i 

77 

Considering  the  very  big  increase  in  crop  often  produced 
by  phosphatic  manures,  and  considering  the  very  small 
risk  of  loss,  every  possible  step  should  be  taken  to  increase 
the  use  of  phosphatic  fertilizers.  Nothing  like  the  amount 
that  ought  to  be  used  is  applied  in  common  practice. 

Great  variation  will  occur  in  the  composition  of  the 
manure,  according  to  the  particular  system  employed. 
Table  10  shows  the  comparison  between  feeding  on  very  wet 
food  and  on  very  dry  food. 

These  conditions  represent  extremes,  but  there  is  much 
room  for  variation  between  these  limits.  When  very  watery 
food  is  fed,  the  amount  of  liquid  manure  is  much  increased, 
and  carries  with  it  a  bigger  quantity  of  dry  material.  In 
both  the  foods  actually  selected  the  amount  of  potassium 
is  high,  and,  therefore,  there  is  ample  to  spare  for  all  purposes, 
D.  4 


50  PLANT  PRODUCTS 

TABLE  10. — POUNDS  TO  OR  FROM  ONE  Cow  IN  ONE  DAY. 


Food.                       Manure. 

Food. 

Manure. 

Total 

1 

Solid.       Liquid.      Solid, 
(Mangels.) 

l                * 

Liquid. 

Solid. 
(Hay.) 

Liquid. 
(Water.) 

Solid. 

Liquid. 

Total 

154 

42 

88 

26 

66 

48 

14 

Water 

135 

35 

84 

4 

66 

38             12 

Dry  matter 

19             — 

7 

4 

22 

— 

10                 2 

N 

0-30  ;     — 

0-14 

O'H 

o'6o 

— 

O'l6    !      O'2I 

p  O5 

0-14  ;     — 

O'lO 

O'OI 

0-15 

— 

0*08 

— 

K2O 

072        — 

0*06 

0-53 

0-49 

— 

O'll 

0*24 

1 

1 

Of  the  nitrogen,  much  better  utilization  is  made  in  the 
more  digestible  and  watery  mangels  than  in  the  dry  and  less 
digestible  hay.  Since  there  is  six  times  as  much  liquid  in 
the  excreta  from  mangels  there  would  have  to  be  used  six 
times  as  much  litter  to  obtain  the  same  degree  of  conser- 
vation. 

Storage  of  Farmyard  Manure. — The  storage  of  the 
manure  heap  is  a  matter  of  considerable  practical  import- 
ance. Soon  after  production  fermentation  begins.  The 
first  fermentation  results  in  converting  urea  into  ammo- 
nium carbonate.  During  this  process  some  ammonia  may 
be  lost  by  fermentation  and  evaporation.  A  good  supply 
of  litter  acts  as  an  absorbant  for  ammonia,  and  the  loss  by 
volatilizing  ammonia  is  probably  very  small  under  ordinary 
farm  conditions,  although  in  town  stables,  where  there  are 
many  highly  fed  horses,  the  loss  of  ammonia  may  be  so 
sufficiently  marked  as  to  be  a  nuisance.  General  decom- 
position produced  by  the  actions  of  various  bacteria  soon 
starts  in  the  manure  heap.  In  broad  outline,  the  anaerobic 
bacteria  attack  the  fibre  and  proteins,  which  they  hydrolyze 
with  the  production  of  gummy  or  colloidal  substances, 
peptones,  and  amino-acids.  The  aerobes  have  little  chance 
of  working  in  a  fresh  manure  heap  ;  they  are  mostly  confined 
to  the  surface,  where  they  are  able  to  carry  on  their  oxidizing 
powers.  The  rate  of  action  will  depend  upon  the  tempera- 
ture, much  liquid  excludes  air,  lowers  the  temperature,  and 
therefore  the  rate  of  decomposition.  Much  carbohydrate 


MIXED  FERTILIZERS  51 

increases  the  speed  of  oxidation,  raises  the  temperature, 
increases  the  general  rate  of  decomposition,  and  sometimes 
assists  in  nitrogen  fixation.  All  the  fertilizing  elements, 
that  is,  nitrogen,  phosphorus,  and  potassium,  increase  the 
rate  of  decomposition,  because  they  facilitate  the  multi- 
plication of  the  bacteria.  As  the  bacterial  food  is  used  up 
the  rate  of  decomposition  slackens. 

Decomposition  in    the    manure  heap  may  proceed    in 
undesirable  directions.     When  nitrogen  is  made  to  change 
into  compounds  unsuited  to  the  growth  of  crops  the  word 
"  denitrification "   is   commonly   applied  to  this  state   of 
affairs.     "  Denitrification  "  is  often  applied  in  two  different 
senses.     Firstly  the  sense  of  the  actual  evolution  of  nitrogen  ; 
this  may  occur  chemically  by  the  interaction  of  nitrous  acid 
upon  ammonia,  or  by  bacterial  evolution  of  nitrogen  from 
proteins.    The  latter  is  probably  only  a  special  case  of  the 
former,  since  the  action  of  nitrous  acid  upon  ammo-acids 
is  directly  comparable  to  its  action  upon  ammonia,  and  such 
changes  are  probably  brought  about  by  bacterial  agencies. 
Once  nitrogen  is  given  off  from  the  manure  heap  as  elementary 
nitrogen  it  becomes  mixed  with  the  nitrogen  of  the  atmosphere 
and  may  be  regarded  from  a  practical  point  of  view  as  finally 
lost.     The  above  is  the  reversal  of  the  process  of  nitrogen 
fixation.     The  other  meaning  of   "  denitrification  "  is  the 
reversal  of  the  process  of  nitrification.     In  the  process  of 
nitrification  the  protein  is  broken  down  to  simpler  organic 
nitrogen  bodies,  then  to  ammonia,  then  to  nitrites,  and  lastly 
to  nitrates.     When  this  process  is  reversed  the  proportion 
of  nitrates  diminishes.     The  reversion  of  nitrogen  can  be 
imitated  in  the  laboratory  by  heating  sugar,  a  nitrate,  and 
potash  in  a  tube,  when  organic  nitrogen  compounds  are 
formed.     In  the  manure  heap  these  changes  are  chiefly 
controlled  by  the  bacteria.     Attempts  to  prevent  the  loss 
of  ammonia  from  the  manure  heap  by  the  addition  of  sub- 
stances of  an  acid  nature  have  done  little  good,  although  for 
town  stables  a  sprinkling  of  gypsum  is  useful  for  sanitary 
purposes. 

The   main    object    of   storage    should    be    to    promote 


PLANT  PRODUCTS 


fermentation,  and  to  prevent  loss  by  drainage.  The  loss  by 
drainage  may  be  very  pronounced,  even  under  carefully 
controlled  conditions.  In  a  series  of  experiments  conducted 
at  Cockle  Park  I  found  the  results  which  are  condensed  in 
Table  n.  The  sampling  of  farmyard  manure  presents  great 
difficulties,  hence  the  error  of  experiment  is  very  large,  but 
in  the  last  column  of  the  table  I  have  expressed  the  average, 
with  the  probable  error  of  the  series. 

TABLE  n. — STORAGE  OF  FARMYARD  MANURE  IN  CEMENT  PITS, 
COCKLE  PARK. 

LOSSES  AND  GAINS  DURING  Six  MONTHS'  STORAGE. 


1899. 

1900. 

1901. 

1902. 

Mean. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Organic  matter 

—  22 

—  20 

-13 

—    I 

-I4±  3 

Mineral  matter 

—    I 

+  22 

—    2 

+  5 

+  6±  4 

Total  nitrogen 

-23 

-29 

-  9 

+    2 

-I5±  6 

Total  phosphoric  acid 

+  16 

-25 

+  39 

—  12 

+  5±n 

Total  potash    .  . 

—  12 

-3° 

-34 

-16 

-23±  5 

It  will  be  seen  that  when  manure  is  kept  in  the  circum- 
stances stated,  the  organic  matter  and  total  nitrogen  that 
are  lost  amount  to  about  15  per  cent.,  within  a  reasonable 
margin  of  error,  that  the  loss  of  potash  is  even  greater,  but 
that  the  phosphoric  acid  gives  no  evidence  of  any  loss.  The 
potash  could,  under  those  circumstances,  only  have  been 
lost  by  drainage  ;  the  nitrogen  might  have  been  lost  either 
by  drainage  or  as  elementary  nitrogen.  About  a  half  of 
the  nitrogen  would  have  been  insoluble  in  water,  and  of  the 
remaining  half  some  at  least  would  have  been  in  the  colloidal 
form,  difficult  of  diffusion.  One  would,  therefore,  expect 
that  if  23  per  cent,  of  potash  can  pass  away  by  drainage, 
the  nitrogen  loss  by  drainage  should  be  less  than  half  that 
figure.  I/ittle  error  in  these  experiments  would  occur  from 
nitrogen  fixation,  since  the  dung  was  made  by  bullocks. 
There  may  be,  therefore,  a  slight  loss  of  nitrogen  into  the 
atmosphere,  but  it  is  very  clear  that  the  most  pressing 
reform  is  to  prevent  loss  by  drainage.  In  places  where  there 
is  a  pit,  to  collect  the  drainage,  the  drainage  is  pumped  up 


MIXED  FERTILIZERS 


53 


by  a  pump  of  the  disc  and  chain  type,  and  allowed  to 
flow  over  the  dry  upper  surface  of  the  manure  heap.  By 
persistently  pumping  the  drainage,  it  evaporates  and  becomes 
concentrated,  and  the  proportion  of  liquor  in  the  pit  becomes 
diminished.  Where  the  manure  is  stored  on  the  field  the 
most  practicable  method  is  to  remove  the  surface  of  the 
ground,  to  break  up  the  subsoil,  to  put  the  manure  on  top, 
to  use  the  earth  that  has  been  dug  out  as  a  cover  for  the 
manure  heap,  and,  when  ready,  to  spread  all  the  manure  and 
all  the  broken  subsoil  on  the  field.  By  such  means  the 
loss  by  drainage  can  be  reduced  to  a  small  figure.  The 
general  analysis  of  farmyard  manure,  kept  under  reasonable 
but  not  ideal  conditions,  is  shown  in  Table  12,  which  gives 
the  probable  composition  of  any  sample  taken  at  random, 
calculated  from  several  analyses. 

TABLE  12. — FARMYARD  MANURE. 


Moisture 
Organic  matter 
Mineral  matter 
Nitrogen  non-albuminoid 
Nitrogen  total   . . 
Potash 
Phosphoric  acid 


Probable  sample. 


75-3    to  80-9 
14-2    to  18-8 
0'43  to    5-9 
0-15  to    0-27 
0-54  to    0-72 
0-52  to    0-68 
0-26  to    0-34 


In  attempting  to  assess  the  money  value  of  any  such 
manure  by  the  same  standard  as  is  adopted  for  chemical  ferti- 
lizers one  will  see  that  the  phosphorus  is  of  little  consequence, 
and  in  any  normal  circumstance  the  price  would  chiefly 
depend  upon  the  nitrogen ;  but  from  a  practical  point  of 
view  the  value  of  the  manure  will  depend  rather  upon  its 
physical  properties  in  the  soil,  upon  its  percentage  of  potash, 
and  upon  its  encouragement  of  the  life  of  soil  organisms. 

It  will  be  quite  impracticable  to  have  every  fertilizer 
employed  on  the  farm  a  quick-acting  one.  Some  of  the 
ingredients  of  any  fertilizer  must  be  of  slow  action  to  provide 
for  the  future.  Farmyard  manure  should,  therefore,  be 
considered  not  in  opposition  to  chemical  fertilizers,  but  in 


54  PLANT  PRODUCTS 

partnership  with  them.  The  chemical  fertilizers  will  supply 
the  quick-acting  and  stimulating  part,  and  the  farmyard 
manure  will  supply  the  more  lasting  and  soil-improving 
part.  With  the  present  lack  of  potash  manuring,  farmyard 
manure  forms  the  chief  source  of  that  element  in  farming. 

The  Utilization  of  Sewage. — The  primitive  system 
of  every  man  to  his  own  land  soon  breaks  down  with 
large  populations.  Simple  closets  are  very  unsatisfactory, 
since  flies  communicate  disease,  and  even  smells  are  lowering 
to  health.  The  earth  closet  is  a  great  improvement  if  enough 
dry  earth  can  be  obtained .  The  resulting  material,  if  removed 
to  the  garden,  provides  a  useful  fertilizer,  but  for  towns  the 
weight  of  the  soil  is  an  insuperable  objection.  Under  the 
systems  where  the  sewage  is  allowed  to  accumulate  in  cess- 
pools great  nuisance  arises.  A  better  system  consists  in 
removing  all  household  refuse  in  carts  at  night.  This 
mixture,  known  as  "  night  soil,"  or  "  Scavenger,"  is  carried 
to  outlying  farms,  and  either  put  direct  upon  the  soil  or 
put  into  trenches  which  have  been  previously  dug.  Farmers 
contract  with  municipalities  to  supply  themselves  and 
neighbours.  Under  these  systems  a  rotation  is  adopted  on 
the  farm  to  suit  periods  of  excessive  manure,  followed  by 
periods  of  no  manure  at  all.  The  details  of  such  management 
on  the  farm  will  depend  largely  upon  the  local  requirements, 
but  the  system  has  been  found  to  work  passably  well  when 
on  a  comparatively  small  scale.  A  more  elaborate  and 
industrialized  system  is  that  generally  known  by  the  French 
name  of  "  Poudrette,"  where  the  night  soil  is  taken  to  a 
factory  and  is  there  mixed  with  a  suitable  proportion  of 
ashes  and  soil,  allowed  to  ferment  over  one  or  two  years, 
and  then  sold  to  the  neighbouring  cultivators.  Such 
Poudrette  contains  about  20  per  cent,  of  water,  10  to  15  per 
cent,  of  organic  matter,  J  to  i  per  cent,  of  nitrogen,  and  J 
to  i  per  cent,  of  phosphoric  acid.  Such  a  factory  must  be 
situated  well  away  from  the  town.  In  very  industrial 
districts  the  night  soil  collected  may  be  taken  to  a  factory 
and  dried,  and-  the  grease  extracted  by  petroleum  spirit, 
the  resulting  material  being  supplied  to  the  farmers  in  the 


MIXED  FERTILIZERS  55 

neighbourhood  as  a  dry  powder.  As  the  phosphoric  acid 
content  is  low,  mineral  phosphates  are  sometimes  admixed. 

For  countries  with  a  plentiful  seaboard  the  water-carriage 
system  supplies  a  simple  solution  of  the  sanitary  difficulties, 
since  everything  may  be  flushed  into  the  sea,  but  such  a 
system  provides  no  solution  of  the  agricultural  side  of  the 
problem.  The  introduction  of  the  sewage  farm. makes  an 
attempt  to  get  over  this  difficulty,  and  utilize  the  manure  for 
food  production.  The  conditions  necessary  for  success  are, 
however,  exceptional.  Where  there  happens  to  exist  a 
suitable  area  of  light  soil,  situated  below  the  level  of  the 
town  supplying  the  sewage,  with  facilities  for  providing 
a  pipe  with  convenient  gradients,  the  system  may  be  a  very 
great  success.  When  only  clay  land  is  available  the  amount 
of  land  necessary  becomes  unreasonably  large,  and  if  too  much 
sewage  is  put  upon  the  land  it  is  ruined  for  years.  Consider- 
able skill  is  therefore  necessary  in  management.  In  some 
cases  the  sewage  farms  originally  succeeded  by  an  accident, 
because  the  condition  of  affairs  caused  an  approximation 
to  bacterial  systems  of  purification.  One  of  the  great 
difficulties  of  a  sewage  farm  lies  in  the  fact  that  it  has  to 
take  sewage  according  to  the  rate  at  which  it  is  being  produced 
in  the  town,  and  not  to  suit  the  requirements  of  the  farm. 
If  it  were  possible  to  entirely  separate  the  rain-water  of  the 
streets  from  the  pure  sewage,  much  of  this  difficulty  would 
be  overcome,  but  it  is  very  difficult  to  satisfactorily  arrange 
a  farm  on  the  system  of  always  having  to  take  manure, 
whether  it  suits  the  crops  or  not.  A  not  infrequent  adjunct 
to  a  successful  sewage  farm  is  a  pig-breeding  establishment, 
as  the  pigs  can  eat  up  the  large  quantities  of  roots,  etc., 
grown  on  a  sewage  farm,  which  fastidious  people  do  not 
fancy.  The  hay  crop  is  also  a  very  important  part  of  a 
sewage  farm,  since  large  crops  of  succulent,  if  coarse,  hay 
can  be  obtained. 

The  Sludge  Precipitation  System.  — To  prevent  the 
nuisance  of  crude  sewage  the  idea  arose  of  precipitating  at 
least  some  of  the  material  as  a  sediment  or  sludge,  and  a  large 
variety  of  patent  mixtures  have  been  used  for  this  purpose. 


56  PLANT  PRODUCTS 

Unfortunately  the  really  valuable  and  important  fertilizing 
ingredients  remain  in  solution,  whilst  the  sludge  is  of 
inferior  composition.  A  very  large  tank  space  is  necessary, 
and  the  materials  obtained  are  of  small  value. 

The  Septic  Tank  Method. — Instead  of  trying  to 
divert  the  normal  course  of  events,  a  system  of  facilitating 
the  natural  decomposition  of  sewage  has  been  introduced 
with  very  considerable  success.  In  the  decomposition  of 
sewage  there  are  roughly  two  stages.  The  first  is  due  to  the 
decomposition  by  anaerobic  bacteria,  much  in  the  same  way 
as  in  the  fermentation  of  farmyard  manure,  described  above. 
During  this  process  the  insoluble  matter  goes  into  solution, 
even  cellulose  becoming  very  largely  decomposed  during  this 
stage.  Subsequently,  the  action  of  aerobic  bacteria  will 
oxidize  the  materials  in  solution,  and  convert  them  into 
inoffensive  materials.  In  practice  it  has  often  been  found 
unnecessary  to  adopt  any  elaborate  plant  to  separate  the 
two  stages,  since  a  preliminary  depositing  tank  of  small 
dimensions,  to  remove  gravel  and  grits,  followed  by  larger 
tanks,  for  the  bacterial  digestion  suffices.  Coke  beds  with 
sprinklers  form  a  favourite  modern  oxidizing  part  of  the 
system.  The  resulting  liquors  contain  practically  everything 
of  value,  and  can  either  be  run  on  to  a  farm,  or  be  run  into 
a  river  without  harm.  The  sludge  from  the  septic  tanks 
is  usually  quite  inoffensive,  but  its  composition  is  very 
variable,  and  the  dry  matter  may  contain  anything  from  \ 
to  2  per  cent,  of  nitrogen.  Not  infrequently  these  sludges 
are  mixed  with  some  phosphatic  fertilizer  to  render  them 
more  generally  useful.  Popular  conceptions  are  apt  to 
exaggerate  the  fertilizing  importance  of  town  sewage.  The 
average  produce  of  one  man  in  one  year  is  about  n  Ibs. 
nitrogen,  2  J  Ibs.  phosphoric  acid,  and  2|  Ibs. potash.  The  sum 
of  all  the  population  is,  no  doubt,  large,  but  the  problem  of 
this  utilization  presents  very  great  difficulties,  excepting  on 
a  small  scale. 

Miscellaneous  Organic  Mixed  Fertilizers. —The  drop- 
pings of  poultry  form  a  very  well-known  and  much-prized 
manure  for  intensive  purposes.  Birds  do  not  secrete  waste 


MIXED  FERTILIZERS  57 

nitrogen  in  the  form  of  urea,  but  in  the  form  of  uric  acid.  The 
nitrogen  is,  therefore,  not  very  soluble  in  water,  although  it 
decomposes  in  the  soil  fairly  rapidly.  The  material  varies 
considerably,  but  about  i  per  cent,  nitrogen,  I  per  cent, 
potash,  and  2  per  cent,  phosphoric  acid  will  represent  a  rough 
average. 

Seaweed  is  a  useful  fertilizer,  available  on  sea-coast 
districts,  where  outlying  rocks  are  covered  with  weed. 
During  certain  stormy  seasons  of  the  year  a  large  amount  of 
seaweed  is  thrown  up  on  the  coast.  Where  this  becomes  a 
nuisance  local  authorities  are  sometimes  prepared  to  carry 
the  seaweed  some  distance  inland  by  traction  engine, 
but  ordinarily  the  farmer's  own  carts  will  have  to  tackle 
the  business.  Seaweed  contains  about  80  per  cent,  water, 
J  per  cent,  nitrogen,  i  per  cent,  potash,  and  J  per  cent, 
phosphoric  acid.  One  of  the  best  uses  for  seaweed  is 
admixture  with  the  ordinary  farmyard  manure  heap.  If 
a  heap  be  composed  of  alternate  layers,  six  inches  of  sea- 
weed and  six  inches  of  farmyard  manure,  the  amount  of 
manure  at  the  farmer's  disposal  is  doubled,  and  the  general 
average  composition  not  very  seriously  affected.  Sea- 
weed can  also  be  used  as  a  convenient  mulch  for  protecting 
young  plants  against  either  drought  or  frost. 

An  important  series  of  mixed  organic  manures  are  included 
in  the  group  known  as  composts.  These  are  conveniently 
made  by  mixing  lime  with  all  kinds  of  waste  organic  material. 
Blood,  to  which  has  been  added  about  2  per  cent,  quicklime, 
sets  into  a  solid  cake,  which  dries  in  the  air,  and  breaks  down 
to  a  powder.  Lime  mixed  with  hedge  clippings,  weeds, 
etc.,  will  gradually  work  down  into  a  convenient  material 
for  subsequent  use.  Attempts  to  ferment  resistant  articles, 
like  bones,  with  either  the  drainings  from  the  manure  heap 
or  fresh  urine,  are  not  very  satisfactory,  because  nearly  half 
of  the  nitrogen  is  lost  during  fermentation. 

Vegetable  or  leaf  mould  is  very  valuable  to  gardeners, 
being  more  like  rich  soil  than  farmyard  manure.  In  forestry 
work  much  importance  is  attached  to  beech  mast,  as  it 
greatly  improves  the  soil  and  facilitates  subsequent  growth, 


58  PLANT  PRODUCTS 

while  carpets  of  pine  needles  form  a  useful  mulch  on  the 
surface,  but  decay  only  very  slowly. 

Peat  is  also  a  material  which  can  be  used  for  fertilizing 
purposes  on  light  sandy  soils,  or  on  heavy  clays.  It  improves 
the  water  supply  and  aeration  of  the  soil.  Much  attention 
has  been  directed  to  the  attempt  to  ferment  peat  into  some- 
thing more  immediately  active.  This  very  old  idea  has  been 
revived  recently,  in  the  effort  to  give  a  carefully  directed 
bacterial  fermentation  in  place  of  a  more  haphazard  decom- 
position. Very  valuable  reports  on  humogen  have  been  given 
by  Voelcker  and  Russell  (see  Bibliography).  Whenever  such 
materials  as  peat,  having  a  very  high  capacity  for  absorbing 
water,  are  added  in  large  quantities  to  a  soil,  they  are  perfectly 
certain  to  produce  a  beneficial  result,  but  the  expense  and 
labour  involved  will  often  detract  from  their  value. 

Conclusion. — The  very  varied  by-products  of  the  in- 
dustries which  are  capable  of  being  used  as  fertilizers  have 
been  discussed  above  in  moderate  detail.  Consultation  with 
the  various  books  referred  to  in  the  Bibliography  will  give 
many  further  details.  Unintelligent  use  of  fertilizers  can 
easily  do  more  harm  than  good,  and  a  knowledge  of  the  proper 
fertilizers  requires  not  merely  a  knowledge  of  the  fertilizers 
themselves,  but  also  of  the  types  of  soil  to  which  they  are  to 
be  applied,  the  crops  proposed  to  be  grown,  and  the  conditions 
under  which  the  cultivation  of  these  crops  is  undertaken. 

REFERENCES  TO  SECTION   IV 

Collins,  "  The  Valuation  of  Manures,"  The  Journ.  of  the  Land  Agents 
Society,  Sept.,  1908,  p.  452. 

Richards,  "  The  Fixation  of  Nitrogen  in  Faeces,"  Journ.  Agric.  Science, 
8,  p.  299. 

Russell  and  Golding,  "  Investigations  on  '  Sickness '  in  Soil,"  Journ. 
Agric.  Science,  5,  27. 

Fowler  and  Clifford,  "Notes  on  the  Composition  of  Sundry  Residual 
Products  from  Sewage,"  Journ.  Soc.  Chem.  Ind.,  1914,  p.  815. 

Rideal,  "  Sewage  and  the  Bacterial  Purification  of  Sewage,"  p.  330. 
(The  Sanitary  Publishing  Co.) 

Dibdin,  "The  Purification  of  Sewage  and  Water,"  p.  108.  (The 
Sanitary  Publishing  Co.) 

Rideal,-  "  Disinfection  and  Disinfectants,"  p.  238.     (Griffin.) 

Weiss,  "  Directions  for  Preparing  Manure  from  Peat,"  Journ.  Board  of 
Agric.,  1916-17,  p.  481. 

Russell,  "  Report  on  Humogen,"  Journ.  Board  of  Agric.,  1917-18,  p.  n. 


MIXED  FERTILIZERS  59 

Bottomley,  "  Bacterised  Peat ;  the  Problem  in  Relation  to  Plant 
Nutrition,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  871. 

Hendrick,  "  The  Value  of  Seaweeds  as  Raw  Materials  for  Chemical 
Industry,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  565. 

"  The  Cultivation  of  Seaweed  in  Ireland,"  Journ.  Board  of  Agric., 
1915-16,  p.  462. 

Hendrick,  "  The  Composition  and  Use  of  Certain  Seaweeds,"  Journ. 
Board  of  Agric.,  1915-16,  p.  1095. 

Voelcker,  Journ.  Roy.  Agric.  Soc.,  1916,  p.  246. 

Aikman,  "  Farmyard  Manure."     (Blackwood.) 


PART  II.— THE   SOIL 

SECTION  I.— SOILS  AND  THEIR  PROPERTIES 

THE  soil  has  two  important  and  entirely  distinct  functions 
for  assisting  the  growth  of  plants,  (a)  To  supply  a  support 
and  room  for  growth,  and  (b)  to  act  as  a  storehouse  for 
plant  foods.  The  first  of  these  functions  is  almost  entirely 
of  a  physical  character,  the  second  is  both  physical  and 
chemical,  and  very  largely  on  the  border-line  between  those 
two  sciences. 

Inspection  of  Soils. — Some  general  observations  can 
be  made  on  the  spot  by  examining  the  soil  in  the  field. 
Whilst  the  analysis  of  soils  is  a  complicated  business,  which 
is  not  treated  in  this  book,  but  left  to  the  text-books  specially 
devoted  to  such  a  very  highly  technical  subject,  yet  the 
preparation  of  a  soil  sample  which  is  required  for  analysis 
is  a  very  important  subject,  and  can  very  rarely  be  carried 
out  by  the  actual  analyst.  For  examining  the  suitability 
of  a  soil  for  specific  crops  and  fertilizers,  a  very  good  plan  is 
to  dig  a  few  holes  in  the  field  and  inspect  the  soil.  Once 
a  hole  has  been  dug  in  the  ground  it  is  easy  to  obtain  a  smooth 
vertically  cut  surface,  which  can  be  observed  without 
disturbing  the  soil.  It  will  generally  be  observed  that  at 
some  depth  the  nature  of  the  soil  changes,  often  fairly 
abruptly.  This  change  is  brought  about  partly  by  the  action 
of  ploughs  opening  the  soil  to  a  particular  depth,  or  by  the 
natural  limitations  imposed  upon  the  vegetation  of  the 
surface. 

When  a  hole  has  been  dug  in  a  field,  and  a  good  vertical 
surface  been  obtained,  it  must  then  be  decided  how  the  slice 
is  to  be  cut,  and  divided  as  regards  depth.  Where  time 


SOILS   AND   THEIR   PROPERTIES  61 

permits,  it  will  be  advisable  to  separate  the  soil  into  a  series 
of  layers,  the  first  three  inches,  the  next  three  inches,  a 
third  three  inches,  and  possibly  a  few  further  depths  as  well. 
A  very  large  number  of  samples  of  soil  have  been  taken  to 
a  depth  of  nine  inches,  and  it  is,  therefore,  desirable,  for 
comparative  purposes,  that  the  amount  of  plant  food  to  a 
depth  of  nine  inches  should  be  known,  but  it  is  often  advisable 
to  have  further  information.  The  great  variation  of  compo- 
sition which  occurs  in  soils  from  depth  to  depth  must  always 
be  borne  in  mind,  since  unless  soils  be  sampled  to  a  definite 
depth,  no  sort  of  constant  results  can  be  obtained.  There 
are,  however,  many  occasions  when  a  soil  is  not  nine  inches 
deep,  and  one  is,  therefore,  compelled  to  content  oneself 
with  less  depth.  Not  infrequently  within  easy  range  of  a 
spade  from  the  surface  one  may  come  across  rock  more 
or  less  broken  down  by  weathering.  Many  attempts  have 
been  made  to  obtain  some  mechanical  appliance  to 'obtain 
samples  of  soil  with  less  labour  than  that  involved  in  fiist 
of  all  digging  a  hole  and  then  obtaining  a  vertical  slice. 
Within  the  narrow  limitations  of  particular  types  of  soil 
such  efforts  are  perfectly  satisfactory,  but  a  universal 
method  for  all  soils  has  yet  to  be  discovered,  excepting  the 
more  laborious  method  here  described.  All  instruments  of 
the  type  of  a  boring  tool  become  unworkable  in  a  soil  con- 
taining many  stones,  whilst  in  humus  soils  they  introduce  the 
serious  difficulty  of  inaccurate  measurement,  owing  to  the 
compression  of  the  soil  which  they  produce.  They  further 
have  the  great  disadvantage  that  the  operator  cannot  see 
the  nature  of  the  soil  he  is  sampling,  and  an  observation 
on  the  spot  of  the  actual  appearance  of  the  undisturbed 
soil  will  often  teach  quite  as  much  as  the  subsequent  analysis. 
The  size  of  the  particles  of  soil  is  a  matter  of  great 
practical  importance.  This  subject  has  been  investigated 
very  fully,  and  much  of  the  literature  on  the  subject  is  given 
under  such  names  as  physical  or  mechanical  analysis.  The 
manner  in  which  the  particles  are  packed  together  is  also 
a  point  of  great  importance.  The  actual  size  of  the  particles 
is  not  easily  altered,  but  the  manner  in  which  particles  are 


62  PLANT  PRODUCTS 

packed  is  subject  to  considerable  control.  If  we  assume, 
for  the  sake  of  argument,  that  all  the  particles  in  the  soil 
are  spherical,  and  that  they  are  packed  together  with  loose 
packing,  then  the  air  space  will  amount  to  47  per  cent,  of 
the  total.  With  close  packing  they  will  give  26  per  cent.  In 
practice,  however,  such  purely  theoretical  considerations  have 
little  relationship  to  what  actually  occurs.  The  particles  are 
not  spherical,  and,  at  any  rate  in  a  temporary  manner,  they 
put  themselves  into  a  condition  known  as  "  crumb  "  structure, 
in  which  the  particles  have  built  themselves  up  into  irregular 
groups,  with  fairly  large  openings  between  groups  of  particles, 
so  that  in  fertile  soils  the  vacant  space  filled  with  either 
air  or  water  amounts  to  about  50  to  70  per  cent.  Where 
there  is  much  fibrous,  half -decayed  root,  the  openings  of 
the  structure,  and  consequently  the  air  and  water  space, 
may  be  further  increased.  In  the  operation  of  tillage  the 
earth  is  broken  apart  and  allowed  to  fall  back  gently,  so 
that  the  structure  is  much  more  open.  Rolling  will  compact 
the  soil  and  decrease  the  air  and  water  content.  For  the 
growth  and  development  of  any  root  system  space  in  the 
soil  is  necessary,  and  the  provision  of  this  necessary  space 
is  largely  dependent  upon  tillage  operations.  The  movement 
of  the  water  in  the  soil  is  much  altered  by  variations  in 
the  open  space  in  the  soil. 

A  very  important  study  in  the  physical  properties  of 
soils  consists  in  the  consideration  of  the  properties  of  colloidal 
material  that  the  soil  contains.  A  rough  distinction  between 
the  colloids  in  the  soil  and  the  solid  grains  may  be  made 
by  stirring  the  soil  up  with  water,  allowing  the  grains  to 
settle  for  twenty-four  hours,  and  pouring  the  muddy  liquid 
off.  Some  portions  of  the  soil  will  practically  never  settle 
in  water,  but  may  be  made  to  do  so  by  precipitating  with 
suitable  agents.  The  addition  of  sodium  carbonate  will 
increase  the  proportion  of  a  soil  that  will  not  settle  in  water. 
The  addition  of  calcium  sulphate  will  precipitate  nearly 
all  the  soil  colloids.  Any  strong  solution — sodium  chloride 
and  sodium  sulphate — will  also  precipitate  the  colloids ; 
super-phosphate,  lime,  basic  slag,  and  farmyard  manure  all 


SOILS  AND   THEIR  PROPERTIES  63 

tend  to  reduce  the  colloidal  condition  of  the  soil.  A  certain 
amount  of  colloid  is  certainly  valuable  in  light  soils.  At 
Woburn  it  has  been  observed  that  nitrate  of  soda  removes 
colloids  from  the  surface  soils,  and  deposits  them  again 
deeper  down,  so  that  the  surface  soil  loses  its  adhesive 
properties,  and  becomes  too  dry  and  sandy.  On  heavy  soils 
too  much  colloidal  matter  makes  the  clay  almost  unworkable. 
It  should  be  noted  that  fertilizers,  in  addition  to  their  purely 
chemical  value,  have  a  powerful  influence  upon  the  colloidal 
character  of  the  soil.  It  is  doubtless  perfectly  possible  that 
in  a  few  special  places  this  influence  of  the  fertilizers  on  the 
colloids  may  help  to  overwhelm  the  influence  of  the  chemical 
elements,  but  in  most  situations  it  will  be  found  that  the 
considerations  given  to  the  fertilizers  in  Part  I.  will  be  a 
fairly  correct  method  of  assessing  the  increment  of  plant 
production.  Nevertheless,  the  secondary  influence  of  the 
fertilizers  upon  the  physical  properties  of  the  soil  must  never 
be  overlooked,  since  it  may  produce  some  profound  changes. 

Personal  observation  shows  that,  on  clay  lands,  basic 
slag  produces  an  abundance  of  deep  fibrous  root,  sulphate 
of  ammonia  a  shallow  black  humus,  and  muriate  of  potash 
a  black  humus  a  few  inches  deep,  with  a  sticky  subsoil. 
On  light  soils,  nitrate  of  soda  gives  a  surface  saiid  with  hard 
pan  subsoil. 

Much  depends  upon  the  ability  for  growth  of  the  surface 
vegetation,  and  this  is  illustrated  in  a  striking  manner  in 
experiments  on  pasture  land.  At  Cockle  Park,  in  North- 
umberland, basic  slag  has  been  continuously  applied  to  grass 
land,  with  the  result  that  the  soil  has  been  steadily  deepened, 
so  that  the  active  part  of  the  soil  on  the  surface  has  invaded 
the  inactive  subsoil  underneath  (see  p.  29).  No  person  to- 
day, who  did  not  know  the  history,  and  was  shown  slices 
of  the  two  soils,  would  imagine  that  they  ever  could  have 
been  the  same.  This  marked  change  in  the  soil  has  been 
brought  about  by  the  increased  root  development  of  the 
natural  vegetation,  which  has  been  encouraged  to  grow  by 
the  application  of  an  appropriate  fertilizer,  in  this  case  basic 
slag.  It  must  not  be  imagined,  however,  that  for  any  and 


64  PLANT  PRODUCTS 

every  soil  exactly  that  treatment  would  be  the  ideal  one, 
but  investigation  on  the  soil  itself  will  probably  show  what 
is  most  required.  Similar  results  have  been  obtained  on 
light  soils  by  combined  potash  and  phosphate  fertilizers, 
whilst  on  some  soils  wild  white  clover  seed  harrowed  in  has 
produced  the  desired  effect. 

Owing  to  the  colloids  in  a  soil,  it  is  difficult  to  filter  a 
soil  extract  through  paper.  A  soil  will,  however,  always 
filter  itself  clear,  since  any  sized  particle  will  always  find  some 
particles  a  little  coarser  than  itself,  the  interstices  between 
which  will  always  be  smaller  than  itself.  By  fitting  up  a 
funnel  with  a  filter  disc  and  cloth,  to  which  is  adapted  a 
long  fall  tube  for  suction  purposes,  and  pouring  the  soil, 
mixed  with  water,  into  the  funnel,  the  first  cloudy  runnings 
can  be  returned  to  the  funnel  and  then  a  clear  solution  will 
be  obtained.  Hence  the  finest  colloids  do  not  penetrate 
very  deeply  into  a  soil. 

Specific  Gravity. — The  true  specific  gravity  of  a  soil — 
that  is,  the  specific  gravity  of  the  particles  of  which  the  soil 
is  composed — is  not  in  itself  a  matter  of  much  practical 
importance,  though  referred  to  in  nearly  all  text-books. 
The  crude  gravity — that  is,  the  weight  of  a  given  volume  of 
soil,  including  air  spaces — is,  however,  a  distinctly  useful 
figure.  Commonly  this  measure  is  expressed  in  pounds  per 
cubic  foot.  A  sand  will  weigh  no  pounds  per  cubic  foot 
when  dry,  a  good  arable  soil  from  80  to  90  pounds,  a  heavy 
clay  75  pounds.  A  soil  containing  very  much  decomposed 
organic  matter  will  weigh  about  70  pounds,  whilst  a  peaty 
soil  containing  much  fibrous  organic  matter  will  only  weigh 
from  30  to  50  pounds  per  cubic  foot.  The  soil  on  Tree  Field, 
at  Cockle  Park,  in  its  unimproved  condition,  weighs  between 
84  and  87  pounds  per  cubic  foot,  and,  though  a  clay,  contains 
a  few  stones  and  a  little  organic  matter.  The  apparent 
heaviness  of  all  the  soils  of  the  Cockle  Park  type  is  due 
rather  to  utter  lack  of  balance  than  to  the  strict  physical 
properties  of  the  fundamental  ingredients,  a  fact  which  is 
borne  out  by  the  above  figures,  which  would  classify  this 
type  of  soil  as  having  a  much  higher  value  than  it  has  in  its 


SOILS  AND  THEIR  PROPERTIES  65 

natural  condition.  Calculated  to  the  weight  of  soil  per 
acre,  taken  to  a  depth  of  eight  inches,  one  acre  would  weigh 
a  thousand  tons  ;  or  to  two  decimetres,  a  million  kilograms. 

Sources  of  Heat  to  the  Soil. — Although  under  con- 
ditions of  market  gardening  and  the  use  01  the  warm 
frame  the  amount  of  heat  produced  by  chemical  action 
may  *  be  appreciable,  in  large-scale  agriculture  the  only 
important  source  of  heat  is  from  the  sun.  The  chief  fluctua- 
tions of  heat  arise  in  (i)  the  photosphere  of  sun  ("  sun 
spots  "),  which  produces  indifferent  harvests  about  once 
every  ten  or  twelve  years  and  fortnightly  alternations  of  high 
and  low  temperatures ;  (2)  the  resistance  of  the  atmosphere 
to  the  passage  of  solar  radiant  energy,  a  resistance  which 
is  greatly  increased  by  clouds,  moisture  and  fog;  (3)  the 
angle  of  incidence  of  the  sun's  rays  upon  the  surface  of 
the  earth,  which  angle  will  vary  with  the  season,  the  latitude, 
and  the  slope  of  the  soil.  Within  the  limits  of  the  tropics, 
that  is,  23°  north  and  south  of  the  equator,  at  some  period 
of  the  year  the  sun's  rays  are  vertical,  and,  according  to 
the  proximity  of  the  equator,  the  sun  even  passes  away 
still  further  from  the  vertical.  In  the  temperate  zones  the 
sun  is  never  absolutely  vertical,  but  owing  to  the  increase 
in  the  length  of  days  during  the  summer,  the  total  amount 
of  solar  radiation  received  within  the  twenty-four  hours 
exceeds  that  received  in  the  tropics.  The  highest  tempera- 
tures ate  recorded  in  latitudes  of  30°  or  thereabouts :  at 
latitudes  over  60°,  solar  radiation  does  not  reach  the  opti- 
mum for  plant  production.  Slopes  having  a  southerly  aspect 
in  the  northern  hemisphere,  or  a  northerly  aspect  in  the 
southern  hemisphere,  are  advantageous,  since  a  definite 
quantity  of  solar  radiation  has  then  a  smaller  area  to 
distribute  itself  over.  In  the  northern  hemisphere  what  the 
southern  slope  of  a  hill  gains  the  northern  slope  loses. 

Altitude  is  an  important  consideration  in  the  growth  of 
plants.  In  high  altitudes  the  sun's  rays  fall  upon  the  ground 
through  a  shorter,  less  dense,  and  clearer  column  of  atmosphere. 
On  the  other  hand,  considerable  lowering  of  temperature 
is  produced  on  high  altitudes  by  ascensional  currents  of 


66  PLANT  PRODUCTS 

air.  When  air  rises  from  the  plains  to  the  hills  it  expands, 
and  in  expanding  loses  heat.  The  wind,  therefore,  rising 
from  the  plains  to  the  hills,  cools  the  tops  of  the  hills. 

In  cold  climates  the  removal  of  superfluous  water  by 
drainage  is  of  great  value  in  maintaining  the  temperature  of 
the  soil.  Hoeing  and  harrowing  also  assist  in  this  direction, 
and  the  use  of  any  kind  of  mulch  effects  the  same  purpose. 
In  hot  climates  irrigation  not  merely  supplies  water,  but  also 
lowers  the  temperature.  Very  shallow  ploughing,  harrowing, 
and  hoeing  make  the  surface  a  relatively  bad  conductor  of 
heat,  and,  therefoie,  prevent  the  penetration  of  solar  heat. 

Colour  of  Soils. — Dark-coloured  soils  absorb  and  radiate 
more  heat  than  light-coloured  soils.  In  hot  climates  some 
of  the  black  soils  show  very  striking  variations  between  the 
temperatures  at  2  p.m.  and  4  a.m.,  as  is  well  known  to  those 
who  camp  out  on  them.  In  damper  climates  the  black  soils 
are  oiten  visited  by  mist  and  fog.  On  the  general  average 
the  black  soils  will  have  a  higher  temperature  than  light 
soils,  since  at  night  they  will  protect  themselves  from  cooling 
by  a  local  blanket  of  fog.  Dark  soils  will  accumulate  more 
dew  than  the  light  soils,  and  are  generally  regarded  with 
favour.  The  origin  of  the  dark  colour  may  be  somewhat 
varied.  It  is  most  frequently  due  to  organic  matter,  either 
produced  by  natural  accumulations  or  by  deliberate  addition 
of  organic  manures.  In  gardens,  in  the  vicinity  of  towns, 
black  colour  is  often  due  partly  to  soot  and  cinders.  The 
real  source  of  the  colour  of  the  Indian  black  cotton  soils  has 
been  much  disputed.  A  red  colour  is  generally  due  to  ferric 
hydrate,  a  blue  colour  to  iron  in  a  lower  stage  of  oxidation. 

Conduction  of  Heat. — Air  is  a  bad  conductor,  and, 
although  silica  is  not  a  particularly  good  one,  it  is  relatively 
better  than  air.  Compact  soils  conduct  heat  best,  and  will 
vary  in  temperature  most.  Superficial  tillage  is,  therefore, 
advantageous.  Observations  under  experimental  conditions 
at  Cockle  Park  for  very  many  years  prove  that  cultivated 
soils  show  less  variation  in  temperature  than  unbilled  land. 
The  best  conductors  of  all  are  moist  gravels,  which  type  of 
soil  produces  the  earliest  crops.  Deep  down  in  the  subsoil 


SOILS  AND   THEIR  PROPERTIES  67 

the  temperature  is  practically  constant.  At  Greenwich 
Observatory  at  a  depth  of  25*6  feet  the  seasons  are  reversed, 
with  a  difference  of  3°  between  summer  and  winter. 

A  very  great  deal  of  attention  has  been  paid  to  what  has 
been  called  mechanical  or  physical  analysis  of  soils.  In  a 
district  where  one  is  dealing  with  geological  strata  which 
have  never  been  seriously  interfered  with  for  many  years 
past  there  is  little  doubt  that  these  methods  have  considerable 
value,  but  where  much  farmyard  manure  and  lime  have  been 
applied  in  the  past,  and  the  surf  ace  of  the  soil  has  beenmodified 
by  road  sweepings,  then  little  value  can  be  attached  to  any 
of  these  methods.  The  books  in  the  bibliography  should 
be  consulted  on  this  highly  technical  subject.  The  fertility 
of  a  soil  is  dependent  upon  an  almost  innumerable  number 
of  factors,  and  which  one  happens  to  be  of  most  importance 
at  the  moment  will  depend  upon  an  almost  innumerable 
number  of  circumstances.  For  example,  many  square 
miles  of  the  Punjab  had  for  thousands  of  years  borne  few 
crops,  but  the  introduction  of  irrigation  has  converted  these 
areas  into  very  fertile  soils,  growing  large  crops  of  wheat  of 
first-class  quality.  Here  the  determining  factor  happens 
to  be  water,  but  the  physical  and  chemical  properties  of  the 
soil  are  the  same.  The  problem  is  an  engineering  one. 
There  are  large  areas  of  very  poor  pasture  in  the  British 
Isles,  such  as  occur  in  Northumberland  in  the  north,  and 
Sussex  in  the  south.  The  application  of  basic  slag  has 
revolutionized  the  whole  character  of  such  soils.  Here  the 
determining  factor  appears  to  be  phosphorus,  and  possibly 
lime  as  well.  In  this  latter  case  chemical  analysis  would  have 
been  of  great  value  for  information,  but  no  single  test,  or 
group  of  tests,  can  possibly  solve  the  problem  of  the  fertility 
of  a  soil.  All  any  such  methods  can  do  is  to  point  out  useful 
lines  of  investigation.  It  must  then  be  left  to  the  cultivator 
to  experiment  upon  the  land,  and  find  out  for  himself  what 
treatment  is  most  satisfactory.  The  great  value  of  both 
physical  and  chemical  analysis  lies  in  suggesting  possible 
systems  of  improvement. 

Capillarity.  — As  is  well  known,  water  will  wet  the  surface 


68  PLANT  PRODUCTS 

of  many  materials.  The  grains  of  the  soil  are  wetted  by 
the  soil  water.  The  soil  water  adheres  as  a  thin  film  to  the 
grains,  and  when  the  grains  are  close  enough  together,  the 
films  unite,  so  that  water  can  pass  from  the  surface  of  one 
grain  to  the  surface  of  the  next,  until  equilibrium  is  reached. 
As  a  consequence  of  this  fact,  water  will  move  through  the 
soil  by  means  of  the  films  adhering  to  the  surface  of  the  soil 
grains.  This  action  is  often  called  capillary  attraction, 
because  it  is  more  conveniently  measured  in  tubes,  but  the 
problem  is  one  of  surfaces,  and  not  tubes.  When  rain  falls 
on  the  soil  the  water  sinks  downwards,  partly  because  of 
the  action  of  gravity,  and  partly  because  capillary  equilibrium 
has  been  upset.  When  evaporation  takes  place  from  the 
surface,  so  that  the  films  of  moisture  adhering  to  the  soil 
grains  become  thin,  then  equilibrium  is  again  established 
by  water  moving  up  from  those  grains  which  are  more 
completely  wetted.  The  rate  of  movement  will  be  dependent 
not  merely  upon  the  motive  power  supplied  by  the  difference 
of  degrees  of  wetness  in  one  part  of  the  soil  and  another, 
and  the  motive  power  of  gravity,  but  also  upon  the  resistance 
due  to  the  varying  viscosity  of  the  soil  water,  and  the 
magnitude  of  the  interstices  between  the  soil  grains. 

It  is  a  common  observation  that  drains  will  run  for  a 
long  time  after  rain  has  fallen.  The  resistance  to  the 
passage  of  water  is  large  in  proportion  to  the  small  motive 
forces,  therefore  velocity  is  low.  As  gravity  is  all  the  time 
acting  upon  any  such  water  in  the  soil,  the  height  to  which 
water  will  rise  by  capillary  action  reaches  a  practical,  if 
not  an  absolute,  limit.  It  is  for  this  reason  that  a  mulch 
on  the  surface  of  the  ground  is  so  often  valuable  in  conserving 
water.  The  water  must  rise  through  the  soil  quicker  than 
evaporation  can  take  place,  otherwise  the  growing  plant  gets 
a  very  poor  share  of  the  water.  The  mulch  allows  water  to 
reach  a  fair  degree  of  concentration  at  the  point  where  the 
plant  roots  are  working.  The  height  to  which  water  will  rise 
by  capillary  action  in  heavy  soils  composed  of  small 
particles  is  greater  than  in  light  soils  composed  of  coarse 
particles,  but  soils  of  a  coarse  character  will  oppose  much 


SOILS  AND   THEIR  PROPERTIES.  69 

less  resistance  to  the  passage  of  water,  and,  therefore,  facili- 
tate rapidity  of  movement.  The  most  suitable  condition  is 
one  intermediate,  where  neither  the  resistance  to  passage  nor 
the  lack  of  capillary  attraction  are  too  pronounced.  Where 
soils  have  been  recently  broken  up  by  tillage  there  will 
always  be  a  space  in  the  soil  which  is  too  large  to  permit  of 
capillary  attraction.  The  water  will,  therefore,  be  obliged 
to  take  circuitous  routes  when  it  rises,  but  the  open  spaces 
permit  the  penetration  of  the  roots,  which  are  thereby  enabled 
to  go  down  after  the  water.  Deep  tillage,  whilst  facilitating 
deep  rooting,  checks  the  upward  movement  of  the  water 
supply  to  the  surface.  Where  rainfall  is  scanty,  deep  tillage 
is  not  satisfactory,  because  the  seeds  that  are  sown  do  not 
easily  get  enough  water  for  their  early  stages  of  growth. 
Very  shallow  tillage  dries  up  an  inch  or  so  of  the  surface, 
but  protects  the  subsoil  from  loss  by  evaporation.  In  some 
special  cases  it  is  possible  to  obtain  a  combination  of  these 
different  effects.  When  turnips  are  sown  on  land  which  has 
been  put  up  into  riggs  and  subsequently  rolled,  the  roller 
only  compresses  the  tops  of  the  riggs,  the  furrows  being 
untouched.  With  a  "  Cambridge "  roller  the  pressure  is 
mostly  on  the  top  of  the  riggs.  Capillarity  is,  therefore, 
increased  about  the  region  where  the  seed  is  sown,  but  a 
mulch  of  loose  earth  remains  in  the  furrows,  and  hinders 
the  development  of  the  weeds. 

A  point  to  be  noted  is  that  evaporation  of  water  from  a 
thoroughly  wet  soil  is  greater  than  that  from  an  equal  area 
of  water  itself,  because  the  surface  of  a  pond  is  practically 
smooth,  whilst  the  surface  of  a  soil  is  very  irregular.  As, 
however,  a  soil  is  by  no  means  always  thoroughly  wetted, 
but  is  often  dry,  the  total  evaporation  in  a  year  from  a  soil 
is  less  than  that  of  an  equal  area  of  water  surface.  At 
Rothamsted,  14  inches  per  annum  represents  the  evaporation 
from  the  soil,  and  18  inches  per  annum  from  a  water  surface. 
In  many  parts  of  the  British  Isles  evaporation  is  greater  than 
at  Rothamsted,  and  in  hot,  dry  countries  the  amount  is 
still  greater.  At  Alice  Springs,  in  South  Australia,  evapora- 
tion amounts  to  103  inches  per  annum,  and  at  Bombay  it 


70  PLANT  PRODUCTS 

is  83  inches.  Any  green  stuff  growing  on  the  surface  of 
soil  will  increase  the  evaporation,  hence  weeds  rob  the  soil 
of  water.  I/oose  stones  on  the  surface  decrease  the  rate  of 
evaporation.  In  some  parts  of  India  stones  that  have  been 
collected  from  the  surface  are  carefully  put  back  again  as  a 
mulch,  but  such  a  method  is  only  possible  in  small  types  of 
cultivation.  When  water  evaporates  the  soil  shrinks  in 
volume,  owing  to  the  removal  of  the  water  films,  which 
separate  the  particles.  In  sandy  soils  this  shrinkage  is 
very  slight ;  with  humus  soils  the  shrinkage  is  very  large 
indeed.  Clay  soils  shrink  to  an  intermediate  extent,  but  do 
not  shrink  in  a  regular  manner,  and  generally  develop  cracks. 
These  cracks  tend  to  break  the  roots  of  plants,  and,  therefore, 
do  harm  at  the  time.  The  surface  soil  collects  in  the  cracks 
and  a  slow  inversion  of  the  soil  takes  place.  In  other  types 
of  soil  cracks  rarely  develop.  Whenever  water  evaporates 
from  a  soil,  loss  of  heat  results,  owing  to  the  latent  heat  of 
steam,  hence  wet  soils  are  also  cold  soils.  When  the  surface 
is  loosened  by  slight  tillage,  the  water  is  kept  in  the  soil. 

At  Cockle  Park  the  moisture  content  on  one  occasion  was 
1 1 -oi  per  cent,  of  water  where  tilled,  and  8-84  per  cent,  of  water 
where  unbilled,  and  on  another  occasion  13*01  per  cent,  where 
tilled,  and  9*53  per  cent,  where  unbilled.  In  very  hot,  dry 
climates  the  capacity  of  dry  soil  to  take  moisture  from  damp 
air  has  some  distinct  value.  Dry  soil  is  distinctly  hygro- 
scopic. During  the  night,  soils  will  radiate  heat,  but  should 
they  condense  moisture  on  their  surface  the  latent  heat  of 
the  water  vapour  will  check  the  drop  in  temperature.  During 
the  day  the  deposited  water  will  evaporate  once  more,  but 
this  time  the  latent  heat  will  check  a  rise  in  temperature. 

Chemistry  of  Soils. — When  any  soil  is  heated,  at 
first  water  is  driven  off,  then  complex  gases  are  produced, 
and  a  certain  amount  of  black  charcoal  left  behind.  The 
charcoal  slowly  burns  off  and  leaves  an  ash,  which  is  generally 
dark  red  in  colour.  During  the  first  of  these  stages  the 
amount  of  water  that  will  be  given  off  will  depend  upon  the 
atmospheric  conditions  prevailing  when  the  sample  of  soil 
was  taken.  When  soils  have  been  wetted  by  rain  and  allowed 


SOILS   AND   THEIR  PROPERTIES  71 

to  drain  for  a  considerable  time,  the  amount  of  water 
remaining  will  vary  according  to  the  physical  properties  of 
the  soil,  as  discussed  above.  In  the  case  of  sands  and  very 
light  soils,  from  5  to  10  per  cent,  of  water  will  be  the  amount 
commonly  reached ;  whilst  in  the  case  of  clays  and  heavy 
soils,  from  30  to  50  per  cent,  will  be  held.  When  the  conditions 
are  very  varied  as  regards  rainfall,  drainage,  etc.,  the  amount 
of  water  found  will  correspondingly  vary  (see  p.  95). 

The  ordinary  figures  of  analysis  are  generally  reckoned 
on  a  soil  which  has  been  dried  at  100°  Centigrade.  In  some 
cases  reference  is  made  to  air-dried  soils  containing  something 
between  2  and  5  per  cent,  of  water.  In  other  cases  120° 
Centigrade  is  taken  as  the  temperature  for  determining  water. 
To  obtain  a  soil  in  complete  solution  only  very  drastic  methods 
will  suffice.  By  ignition  at  a  red  heat  the  whole  organic 
matter  is  driven  off,  and  by  the  subsequent  action  of  hydro- 
fluoric acid  the  silica  is  volatilized,  and  the  remaining 
substances  go  into  solution.  It  is  very  rare  indeed  that 
the  information  obtainable  by  solution  in  hydrofluoric  acid 
has  any  agricultural  value,  as  neither  the  plant  nor  the  soil 
bacteria  nor  atmospherical  agents  can  possibly  compare 
with  hydrofluoric  acid.  The  strongest  acid  commonly 
employed  in  the  laboratory  is  strong  hydrochloric  acid. 
For  many  purposes  the  information  obtainable  from  ex- 
traction by  very  weak  solvents  is  of  much  greater  value 
than  infoimation  obtainable  by  more  drastic  chemical 
agents.  Experience  and  convenience  show  that  a  solution 
of  I  per  cent,  citric  acid,  as  recommended  by  Dr.  Bernard 
Dyer,  is  one  of  the  best  of  the  weak  solvents.  It  is  usual 
in  laboratories  to  shake  a  mixture  of  the  soil  with  I  per  cent, 
citric  acid  by  hand  at  intervals  for  three  to  six  days,  or  to 
agitate  in  a  mechanical  shaker  for  about  twelve  hours. 
Of  the  ingredients  usually  discovered  by  chemical  exami- 
nation we  have,  among  the  mineral  portions,  the  following 
materials  : — 

Iron. — This  element  occurs  chiefly  as  ferric  hydrate, 
and  partly  as  ferric  silicates,  but,  under  exceptional  circum- 
stances, as  ferrous  compounds  and  pyrites.  All  fertile 


72  PLANT  PRODUCTS 

soils  contain  their  iron  in  the  ferric  condition,  lower  conditions 
of  oxidation  are  prejudicial  to  plant  life. 

Aluminium. — This  element  occurs  in  combination 
with  silica.  Substances  like  felspars  are  not  infrequently 
present  in  soils.  Those  felspars  which  contain  potassium 
are  fairly  resistant  to  weathering,  but  those  containing  much 
sodium  are  more  readily  weathered  down.  Clay  soils  contain 
a  larger  proportion  of  aluminium  compounds  than  are  found 
in  sands.  The  aluminium  probably  plays  but  a  small  part 
in  the  chemical  changes  of  the  soil,  excepting  so  far  as  it  is 
one  of  the  constituents  of  complex  silicates. 

Manganese. — Manganese  is  present  in  most  soils  to 
a  very  small  extent,  but  occasionally  the  amount  rises 
as  high  as  i  per  cent.  It  is  possibly  an  element  of  some 
importance,  as  it  is  found  invariably  in  beech  trees,  and  is 
a  very  common  constituent  of  grass  and  root  crops,  but 
the  amounts  present  are  small.  The  red  colour  of  the  red 
beech  leaf  and  red  hair  is  believed  to  be  due  to  manganese 
compounds. 

Titanium  is  always  present  in  soil  to  the  extent  of 
a  per  cent,  or  so,  but  is  commonly  left  mixed  with  silica  in 
analytical  returns.  It  is  not  known  to  have  any  value. 

Calcium. — This  element  is  one  of  the  most  important 
in  the  soil.  The  most  useful  form  is  calcium  carbonate, 
which  by  slow  solution  in  water  containing  carbon  dioxide 
becomes  calcium  bi-carbonate,  an  important  agent  in  the 
process  of  nitrification,  and  in  the  flocculation  of  clays. 
Calcium  sulphate  is  often  present  in  small  amounts.  The 
oxidation  of  sulphur  compounds  in  the  soil  will  result  in 
the  production  of  calcium  sulphate  with  the  aid  of  some 
source  of  lime.  Complex  compounds  of  calcium  with 
siliceous  substances,  and  complex  calcium  compounds  with 
organic  materials,  are  of  only  slightly  less  importance  than 
calcium  carbonate.  These  compounds  are  respectively 
alluded  to  by  the  vague  general  terms  of  calcium  silicates 
and  calcium  humates.  It  must  not  be  supposed  that  the 
constitution  of  cither  of  these  bodies  is  known.  These 
names  are  only  general  terms  expressing  groups  of  compounds 


SOILS  AND   THEIR  PROPERTIES  73 

having  certain  common  properties.  When  such  substances 
as  sulphate  of  ammonia  come  into  contact  with  "  calcium 
silicate  or  humate,"  the  sulphuric  acid  part  of  the  sulphate 
of  ammonia  combines  with  the  calcium,  whilst  the  ammonia 
enters  into  combination  with  the  silicic  or  humic  residue. 
Such  actions  are  not  so  beneficial  to  the  soil  as  the  actions 
of  the  same  fertilizer  on  calcium  carbonate.  It  is  only  where 
plant  production  is  carried  out  to  a  low  degree  that  calcium 
silicate  and  humate  can  be  considered  as  a  substitute  for 
calcium  carbonate.  Intensive  plant  production  necessitates 
the  presence  of  calcium  carbonate.  Water  containing 
carbon  dioxide  can  also  react  with  these  "  calcium  silicates 
or  humates,"  producing  calcium  bi-carbonate.  The  presence 
of  calcium  carbonate  can  be  detected  by  the  degree  of 
effervescence  which  is  produced  on  the  addition  of  hydro- 
chloric acid.  A  little  experience  will  enable  one  to  judge 
fairly  well  of  this  point,  but  sodium  carbonate  and  magnesium 
carbonate  will  give  the  same  effervescence.  For  most 
purposes  a  knowledge  of  the  carbonate  present  is  of  more  use 
than  a  knowledge  of  the  actual  amount  of  calcium  (see  p.  75). 
Calcium  carbonate  checks  "finger  and  toe  "  in  turnips. 

Magnesium. — Magnesium  in  the  soil  will  generally 
occur  as  magnesium  carbonate,  magnesium  bi-carbonate, 
complex  magnesium  silicates,  magnesium  humates,  and, 
very  rarely,  traces  of  magnesium  sulphate  or  chloride. 
Magnesium  is  certainly  a  necessity  of  plant  life,  and  is 
stored  in  the  cereal  seeds  to  an  appreciable  extent.  Soils 
very  deficient  in  magnesia  show  beneficial  results  from  the 
application  of  magnesium  carbonate,  but  soils  containing 
much  magnesia  usually  show  bad  results  from  the  addition 
of  magnesium  carbonate.  A  theory  has  been  suggested  that 
the  ratio  of  magnesia  to  lime  is  important  in  plant  life. 
A  soil  in  County  Durham,  for  example,  which  has  failed 
both  for  agriculture  and  forestry  shows  CaO:MgO::  1:9*2. 
There  is  some  evidence  in  support  of  this  view,  but  it  is  so 
much  disguised  by  other  factors  that  at  present  the  subject 
must  be  left  open  to  doubt.  There  is  no  question  that  soils 
containing  much  magnesia  are  generally  benefited  by  an 


74  PLANT  PRODUCTS 

application  of  lime,  but  that  is  also  true  of  soils  which  contain 
but  little  magnesia.  There  is  also  plenty  of  evidence  that 
the  general  balance  of  fertilizing  ingredients  in  a  soil  is  an 
important  point,  and  whether  the  lime  -magnesia  ratio  has 
any  specially  great  importance  beyond  other  ratios,  say 
lime  to  iron,  is  a  point  which  has  not  yet  been  satisfactorily 
settled  (seep.  8). 

Potassium. — Potassium  occurs  chiefly  in  the  soil  as 
felspars,  hornblende,  and  other  minerals.  A  fair  proportion 
of  potassium  in  the  soil  also  occurs  in  combination  with 
organic  matter,  which  is  commonly  known  as  potassium 
humate.  A  certain  quantity  of  soluble  silicates  containing 
potassium  occurs  in  soil  water.  The  proportion  of  potash 
extracted  by  weak  acids  is  very  small  indeed,  sometimes  only 
a  fiftieth  part  of  the  total  potash  in  a  soil  is  capable  of  being 
dissolved  by  a  i  per  cent,  solution  of  citric  acid. 

Sodium. — Sodium  occurs  chiefly  in  silicates  of  a  complex 
type,  which  are  not  so  stable  as  the  corresponding  potassium 
compounds.  The  action  of  weathering  these  silicates 
results  in  the  production  of  sodium  bi-carbonate,  which, 
reacting  upon  the  fine  clay  particles,  produces  a  sticky  and 
impervious  mass.  In  some  parts  of  the  world,  such  as  India 
and  the  United  States  of  America,  salt  incrustations  on  soils 
are  common,  ruining  many  miles  of  otherwise  good  soil. 
Where  there  is  little  organic  matter  the  incrustation  is 
white,  where  there  is  much  the  colour  is  often  black.  The 
terms,  reh,  usar,  white  alkali,  black  alkali,  are  the  common 
names  for  this  type  of  soil.  lyack  of  drainage  is  one  of  the 
chief  causes  of  the  serious  accumulation  of  sodium  salts  in 
a  soil.  The  addition  of  calcium  sulphate  in  any  form  will 
result  in  flocculating  the  clay,  and,  therefore,  in  improving 
the  drainage.  The  mere  operation  of  cultivation  will  also 
assist  in  improving  the  drainage  and  thereby  prevent  the 
accumulation  of  soda.  Sodium  has  no  particular  value  to 
the  soil,  and  is,  therefore,  often  omitted  from  analyses. 

Phosphoric  Acid. — The  only  compounds  of  phos- 
phoric acid  that  are  found  in  the  soil  are  derived  from 
ortho-phosphoric  acid.  Phosphoric  acid  is,  of  course,  a 


SOILS  AND   THEIR  PROPERTIES  75 

most  important  ingredient  in  soils.  Probably  phosphorus 
and  nitrogen  are  the  two  most  commonly  lacking  soil 
ingredients.  Ferric  hydrate  in  the  soil  is  capable  of  combining 
with  phosphoric  acid  and  forming  insoluble  phosphates, 
which  undoubtedly  react  to  a  limited  extent  with  calcium 
salts,  so  that  in  the  soil  phosphorus  will  occur  as  phosphates 
of  all  the  bases,  and  will  also  be  found  in  the  organic  matter. 
Water  containing  carbonic  acid  is  a  better  solvent  of  the 
complex  phosphates  than  water  itself,  and  the  amount  that 
will  enter  into  solution  will  depend  partly  upon  the 
concentration  of  carbonic  acid  in  the  water  of  the  soil,  which 
will  in  turn  depend  on  the  percentage  of  carbon  dioxide  in 
the  soil  atmosphere.  I^arge  amounts  of  iron  in  the  soil 
hinder  the  solution  of  the  phosphoric  acid  by  carbonic  acid. 

Sulphuric  Acid. — Sulphuric  acid  in  the  form  of 
calcium  sulphate  is  common  in  all  soils,  and  is  probably  the 
chief  source  of  the  sulphur  that  is  necessary  for  the  formation 
of  plant  proteins.  It  is  being  incessantly  regenerated  in 
the  soil  itself  by  the  oxidation  of  organic  sulphur  compounds 
acting  upon  lime,  also  present  in  the  soil.  In  the  vicinity 
of  large  towns  the  sulphur  thrown  into  the  atmosphere  by 
the  combustion  of  coal  comes  down  with  the  rain,  washes 
into  the  soil,  combines  with  lime,  and  produces  calcium 
sulphate.  Where  the  amount  of  lime  is  insufficient,  the  soil 
becomes  acid,  and  less  fertile.  Whenever  super-phosphate 
or  sulphate  of  ammonia  are  used,  considerable  quantities 
of  sulphuric  acid  are  added  to  the  soil,  so  that  modern 
conditions  of  agriculture  near  big  industrial  districts  do  not 
usually  require  the  addition  of  sulphate  to  the  soil,  but 
agricultural  districts  far  removed  from  industrial  scenes  may 
show  a  deficiency  of  this  element. 

Carbonic  Acid. — Carbonic  acid  occurs  in  the  soil 
both  in  the  free  and  combined  condition.  When  carbon 
dioxide  in  the  air  dissolves  in  water  a  certain  amount  of 
the  true  carbonic  acid  exists  in  solution,  and  acting  upon 
any  base  present,  produces  bi-carbonate.  When  such  soil  is 
dried,  and  removed  to  the  laboratory,  an  ordinary  carbonate 
is  formed.  The  amount  of  calcium  carbonate  in  the  soil 


76  PLANT  PRODUCTS 

is  one  of  the  most  important  points,  since  the  effective  use 
of  most  manures  will  be  largely  determined  by  its  presence 
in  sufficient  amount.  More  than  I  per  cent,  of  calcium 
carbonate  is  probably  unnecessary,  and  less  than  I  per  cent, 
is  probably  only  suitable  to  parsimonious  systems  of  farming. 

Nitric  Acid. — The  nitrates  in  the  soil  are  very 
evanescent.  The  plant  gradually  sucks  them  up  and  is 
quite  prepared  to  store  them  in  the  stem  if  it  has  the  good 
luck  to  find  more  than  a  scanty  supply.  The  bacteria  in 
the  soil  will  readily  steal  the  oxygen  of  the  nitrates  if  there 
is  much  undecomposed  organic  matter  present.  On  the 
other  hand,  nitrates  are  being  incessantly  produced  by  the 
beneficial  action  of  bacteria  in  the  soil.  The  amount  of 
nitrate  in  a  soil  is  rather  an  evidence  of  the  vigour  of  life  in 
the  soil  than  of  anything  else.  Nitrates  are  washed  out  of 
the  soil  with  great  ease  and  rapidity. 

The  Organic  Matter  in  the  Soil. — The  ordinary  process 
of  drying  a  soil  in  a  water  oven  and  then  igniting  gives  a 
figure  which  represents  both  the  organic  matter  and  water 
of  combination  together.  The  latter  figure  is,  of  course, 
not  constant,  and  depends  upon  the  amount  of  hydrated 
silicates  present.  The  figure  for  oiganic  matter  in  a  soil 
will,  therefore,  be  nearer  the  mark  in  a  sandy  soil  than  it 
is  in  a  clay  soil.  Much  labour  has  been  devoted  to  studying 
the  organic  matter  in  the  soil,  but  it  is  such  a  very  difficult 
problem  that  it  is  almost  impossible  to  give  any  wide  view 
of  the  subject.  The  mere  estimation  of  the  carbon  will  not 
give  one  much  insight,  whilst  the  efforts  to  extract  so-called 
humic  acid  only  touch  the  fringe  of  the  question.  Some  idea 
of  the  amount  of  decomposed  organic  matter  can  certainly 
be  obtained  by  a  modification  of  Grandeau's  method,  that 
is,  by  first  acidifying  the  soil,  washing  out  all  calcium 
compounds,  extracting  with  dilute  ammonia,  and  comparing 
the  colours  obtained.  An  estimation  of  nitrogen  is  certainly 
valuable,  and  helps  to  give  one  some  idea  of  the  amount  of 
organic  matter  present.  The  ratio  of  carbon  to  nitrogen 
was  investigated  by  I^awes  and  Gilbert  at  Rothamsted, 
who  found  that  carbon  was  oxidized  away  from  the  soil 


SOILS   AND   THEIR  PROPERTIES  77 

faster  than  nitrogen.     Those  authors  showed  that  in  farm- 
yard manure  the  ratio  C  to  N  equals  25  to  i.     In  the  top 
nine  inches  of  old  pasture  the  ratio  was  13  to  i,  but  in  the 
subsoil  6  to  i.     Some  of  the  American  workers  on  the  subject 
have  detected  small  traces  of  a  variety  of  synthetic  compounds, 
but  it  is  very  difficult  to  decide  whether  these  are  important 
or  not.     We  have  so  many  illustrations  in  living  things  of 
the  extraordinary  potency  of  small  traces  that  it  does  not 
do  to  ignore  little  things,  but  until  something  more  definite 
is  known  it  is  not  practicable  in  a  conspectus  of  this  character 
to  do  much  more  than  refer  to  the  authors  in  the  bibliography. 
Available  Plant  Food. — A  very  distinct  advance  was 
made  in  soil  analysis  when  Dr.  Bernard  Dyer  introduced 
his   method  of   attacking  soils   by  i   per  cent,  citric  acid 
solution    (see    Bibliography).     Dyer   showed   that    for   the 
less  exhausting    crops   0*01   per   cent,  of   phosphoric  acid 
or  potash,  soluble  in  i  per  cent,  citric  acid,  represented 
the  margin  between  fertility   and  need  of  manure.     The 
method  has  also  been  found  to  apply  to  tropical  soils.     It 
has  been  pointed  out  that  the  method  of  Dyer  is  purely 
empirical  and  that  if  carried  out  under  totally  different 
conditions  different  results  will  be  obtained,  but  the  strength 
of  Dyer's  position  lay  in  the  fact  that  he  correlated  his  method 
with    actual    experiments  at    Rothamsted,   and    that    his 
conclusions  have,  in  the  main,  been  thoroughly  well  sub- 
stantiated in  most  places  where  they  have  been  tried.     The 
objections    raised    against    his    method    are    only    general 
objections  to  any  single  test ;  so  far  as  a  single  test  is  capable 
of  use  at  all,  there  are  few  single  tests  applicable  to  soils  of 
such  general  utility  as  the  phosphoric   acid  and  potash 
soluble  in  i  per  cent,  of  citric  acid.     The  relationship  of 
the  soil  to  the  soil  water,  to  the  plant,  or  to  a  I  per  cent, 
solution  of  citric  acid,  are  all  cases  of  mass  action.    The  state- 
ment that  repeated  extractions  with  citric  acid  continue 
to  dissolve  more  and  more  phosphoric  acid  from  the  soil 
is  not  a  criticism  of  Dyer's  method  at  all,  but  an  explana- 
tion of  the  reason  of  its  success.     It  is  just  because  citric 
acid  and  carbonic  acid  and  the  plant  in  relation  to  the  soil 


78 


PLANT  PRODUCTS 


are  all  cases  of  reversible  reaction,  that  the  extraction  with 
weak  solvents  is  some  kind  of  analogue  to  the  life  of  the  plant. 
The  complete  analysis  of  soils  is  given  in  many  text-books, 
but  only  one  or  two  illustrations  can  be  found  room  for  here. 
Whatever  part  of  the  world  soils  come  from,  there  is  some 
kind  of  resemblance.  The  following  table,  taken  from  a 
book  by  the  author,  gives  the  composition  of  a  few  Indian 
soils,  to  which  have  been  appended  one  or  two  analyses  from 
Northumberland. 

TABLE  13. 


Indo-Gangetic  alluvium. 

Madras. 

Northumber- 
land. 

Sand. 

Loam. 

Clay. 

Calca- 
reous. 

Sand. 

Red 
sand. 

Loam. 

Heavy. 

Light. 

Sand  and  Insoluble 

Silicates 

89-92 

82*91 

75.69 

57'52 

92-25 

84-44 

72-96 

76-21 

83-20 

Iron  (Fe2O3) 

2-70 

5-00 

6-80 

3'23 

2H5 

5*30 

8-70 

— 

2-77 

Alumina  (A12O3) 
Manganese  (MnO) 

3-65 

5-30 
0-13 

8-00 

0-13 

3'39 

i'75 

0-04 

5'7i 

0-08 

9-70 
0-15 



3*51 

Lime  (CaO) 

0-41 

I'OO 

I  -60 

*4'54 

0-13 

o'53 

1-50 

0-69 

0-25 

Magnesia  (MgO)  .  . 

o*55 

1-40 

I-50 

1-86 

°'33 

o'54 

O'lO 

0-65 

— 

Potash  (K2O)      .  . 

0-49 

0-52 

0-44 

0-06 

0-16 

0-27 

O'5O 

0-31 

0-64 

Soda  (Na20) 

0-09 

0'20 

0-02 

0-06 

0-15 

o'75 

— 

— 

Phosphoric     Acid 

(P206)  .. 

0-08 

0-I3 

0-09 

0-18 

0-05 

0-09 

O'lO 

0-07 

0*07 

Sulphuric        Acid 
(SO,)     .. 

o'°5 

O"O2 

0-08 

_ 

__ 

_ 

_ 

_ 

Carbonic         Acid 

(CO,)     .. 

0-32 

0-71 

o*55 

11*42 

O'll 

0-24 

0-07 

O'OI 

O'OI 

Combined     water 

and         organic 

matter 

I-74 

2-70 

5-00 

7'32 

2-77 

2-76 

5'7° 

9-31 

8-40 

Nitrogen  N 

0-054 

O'O7O 

0-052 

0-180 

0*013 

0-016 

o'°55 

O'2O 

o'i6 

Available  P2O6   .  . 

O'OIO 

0-015 

O'OIO 

—  . 

O'O22 

O'OI2 

0*016 

0*05 

0-15 

K20     .. 

O'OIO 

O-OI5 

O'OIO 

— 

.  —  . 

— 

— 

0-15 

0-05 

Stones  over  3  mm. 

— 



— 

—     |     — 

— 

— 

2-0 

Coarse  Sand  3-0*5 

mm  

—  . 



— 

— 



— 

— 

I'O 

24-0 

Medium  Sand  0-5- 

0*25  mm. 

— 



— 

— 



— 

— 

2-0 

35'° 

Fine  Sand  0*25-0'  i 

mm. 

~ 

~~— 

j 

~ 

~ 

~ 

4-0 

n-o 

To  interpret  any  soil  analysis  the  most  important  points 
to  consider  are  the  following.  Sand  and  insoluble  silicates 
often  give  a  clue  to  the  physical  condition  of  the  soil. 
L,uxmore  showed  the  correlation  between  insoluble  silicates 


SOILS  AND   THEIR  PROPERTIES  79 

and  mechanical  analysis.  Soils  containing  large  percentages 
of  sand  and  insoluble  silicates  are  of  a  light,  sandy  character, 
those  containing  low  amounts  are  of  a  heavy  clay  character, 
unless,  when  we  must  always  reconsider  the  results  of  physical 
analyses,  the  soil  also  contains  much  lime  or  organic  matter. 
Soils  containing  much  iron  are  hungry  for  phosphoric  acid, 
though  when  supplied  with  phosphoric  acid  they  usually 
become  very  fertile  soils.  The  aluminium  is  an  indication 
of  the  amount  of  clay  present.  Manganese  has  little  general 
interest,  although  there  is  distinct  evidence  that  small 
quantities  of  manganese  are  useful  (see  p.  9).  The  lime 
is  a  most  important  ingredient,  and  when  the  lime  falls  to 
low  figures  fertility  is  at  a  low  ebb.  Magnesia  in  small 
quantities  is  probably  beneficial,  in  large  quantities  it  appears 
to  be  haimful.  The  ratio  of  lime  to  magnesia  is  sometimes 
considered  important.  Where  the  magnesia  exceeds  the 
lime  there  is  considerable  evidence  that  the  magnesia  is 
harmful.  The  potash  extractable  by  hydrochloric  acid  is 
a  figure  of  no  practical  value.  The  phosphoric  acid  dissolved 
by  hydrochloric  acid  should  not  fall  below  0*1  per  cent. 
Sulphuric  acid  may  be  ignored  except  in  districts  where  there 
is  no  coal  smoke  and  little  artificial  manure  used.  The 
carbonic  acid  evolved  in  the  cold  by  dilute  acids  is  valuable 
as  an  indication  of  the  amount  of  calcium  carbonate  in  the 
soil.  It  will  be  noticed  in  the  figures  given  that  the  organic 
matter  and  water  of  combination  in  Northumberland  are 
very  high  in  proportion  to  those  in  the  Indian  soils  quoted. 
This  is  quite  typical  of  the  difference  between  cold  and  hot 
climates.  The  nitrogen  is  usually  very  low  in  well-cultivated 
soils  in  hot  countries  and  high  in  forest  or  pasture  in  cold 
climates.  The  figures  for  nitrogen  can  only  be  taken  in 
conjunction  with  other  evidence.  The  available  phosphoric 
acid  and  potash  soluble  in  i  per  cent,  citric  acid  form  some  of 
the  most  useful  figures  in  the  table.  Much,  of  course,  will 
depend  upon  the  kind  of  crop  grown,  but  for  crops  of  no 
great  exhaustive  character,  0*01  per  cent,  will  make  a  good 
dividing  line  between  fertility  and  need  of  manure.  In 
considering  the  chemistry  of  soils  one  should  consider  rather 


8o  PLANT  PRODUCTS 

the  balance  of  the  ingredients  than  their  absolute  amounts 
(see  p.  8).  Exactly  what  balance  is  necessary  for  any  set  of 
circumstances  is  only  approximately  known,  and  the  actual 
cultivator  will  need  to  experiment  for  himself  on  his  own 
soil. 

Nitrification  in  Soils.— The  air  in  the  soil  differs  from 
ordinary  air  in  that  it  contains  less  oxygen  and  more  carbonic 
acid,  owing  to  the  oxidation  of  organic  matter  in  the  soil  by 
the  action  of  the  air.  As  two  volumes  of  oxygen  produce  two 
volumes  of  carbon  dioxide,  this  change  does  not  effect  the  per- 
centage of  nitrogen.  Some  small  quantities  of  nitrogen  may 
be  taken  out  of  the  air  by  nitrogen  fixing  bacteria,  and  some 
small  quantities  of  nitrogen  may  be  added  by  de nitrification. 
The  atmosphere  in  the  soil  and  the  ordinary  atmosphere  above 
the  surface  diffuse  into  one  another.  The  rate  at  which 
this  diffusion  will  take  place  is  lessened  by  compression, 
but  is  fairly  independent  of  the  fineness  or  coarseness  of 
the  particles  of  the  soil.  The  effect  of  rolling  the  soil  will 
be  to  first  compress  the  soil,  prevent  diffusion  taking  place, 
and,  therefore,  increase  the  percentage  of  carbon  dioxide. 
When  the  percentage  of  carbon  dioxide  in  the  soil-air 
increases,  the  amount  of  carbon  dioxide  dissolved  in  the  soil 
water  will  also  increase,  since  the  amount  dissolved  depends 
upon  the  partial  pressure  of  the  carbon  dioxide. 

As  the  amount  of  carbonic  acid  dissolved  in  water  increases, 
so  the  solvent  action  of  the  soil  water  increases  at  the  same 
time.  Rolling,  however,  by  checking  the  diffusion  of  fresh 
air  into  the  soil,  lowers  the  percentage  ot  oxygen  and  dis- 
courages oxidizing  bacteria.  The  ultimate  effect  of  rolling 
the  soil  is,  therefore,  to  increase  the  supply  of  phosphorus 
and  potassium  to  the  plant,  and  decrease  the  supply  of 
nitrogen.  Opening  up  the  soil  by  harrowing  produces  the 
opposite  effects.  These  effects  are,  however,  very  temporary, 
since  secondary  results,  due  to  bacterial  life,  quickly  come 
into  play.  In  addition  to  the  soil  atmosphere  considerable 
quantities  of  gas  are  occluded  on  the  surface  of  the  soil 
particles.  Ferric  hydrate  is  particularly  powerful  in  this 
respect.  Peat,  and  all  other  forms  of  organic  matter,  are 


SOILS  AND   THEIR  PROPERTIES  81 

also  good  substances  for  occluding  gas.  Gases  occluded  on 
the  surface  are  more  active  than  ordinary  gases,  but  little 
work  has  been  done  to  follow  up  exactly  what  effect  this  has 
upon  soil  life.  The  action  of  occluded  gas  is  probably 
generally  overwhelmed  by  bacterial  actions,  to  which  much 
more  attention  has  been  paid.  Russell  and  Hutchinson  have 
shown  that,  in  addition  to  the  bacteria  in  the  soil,  there 
are  considerable  numbers  of  bacterial  enemies,  which  reduce 
the  numbers  of  the  bacteria.  Whether  the  idea  that  soil 
amoebae  and  paramecia  play  the  part  of  microscopic 
beasts  of  prey  is  a  true  or  only  a  fancy  picture  has  never 
been  determined,  but  the  ultimate  results  have  been  the 
subject  of  careful  investigation.  Certain  organisms  living 
in  the  soil  are  able  to  fix  nitrogen,  provided  they  can  obtain 
organic  matter  in  some  way,  and  provided  they  can  obtain 
a  proper  supply  of  phosphates  and  potash  (see  p.  29). 

At  Cockle  Park,  in  Northumberland,  the  amount  of 
nitrogen  in  the  soil  has  been  steadily  increased  by  the 
application  of  phosphatic  manures.  The  plot  which  received 
no  manure  has  steadily  decreased  in  its  nitrogen  content  from 
0*197  per  cent,  nitrogen  in  1899  to  0*174  Per  cent,  in  1916, 
whilst  the  plot  that  was  treated  with  basic  slag  reached 
0*227  Per  cent,  nitrogen  in  1908  and  0*244  per  cent,  in  1916. 
All  these  figures  refer  to  the  top  six  inches  of  soil,  and  have 
for  the  most  part  been  done  in  duplicate  or  triplicate,  show- 
ing probable  errors  varying  from  nothing  to  0*008  per  cent. 
Other  plots  with  other  treatments  have  shown  somewhat 
similar  results.  That  this  fixation  of  nitrogen  is  by  no 
means  purely  superficial  is  also  shown  in  these  Cockle  Park 
experiments  by  taking  the  soil  to  each  three  inches  depth. 
In  1916  the  unmanured  plot  gave  at  each  three  inches  step 
the  following  figures  :  0*217,  0*131,  0*100,  0*070,  and  the 
corresponding  figures  for  the  manured  plot  were,  0*304,  0*184, 
0*137,  0*100.  It  will  be  noted  that  the  improvement  is  very 
marked  in  the  top  three  inches,  slightly  less  marked  in  the 
next  three  inches,  while  in  the  depths  from  six  to  nine  inches, 
and  from  nine  to  twelve  inches,  there  is  still  a  steady  increase. 
The  gain  in  nitrogen  is  clearly  still  proceeding  at  all  layers 
D.  6 


82  PLANT  PRODUCTS 

in  the  soil,  and  is  still  going  down  deeper  and  deeper.  The 
fixation  of  nitrogen  in  soil  is  usually  dependent  upon  the 
presence  of  leguminous  crops.  At  Cockle  Park  the  leguminous 
crop  concerned  is  undoubtedly  wild  white  clover,  but 
in  different  parts  of  the  world  other  leguminous  crops  would 
play  the  same  part.  Nitrogen  that  has  been  fixed  in  the 
soil,  or  obtained  in  the  soil  by  any  other  means,  is  converted 
by  other  soil  bacteria  into  nitrites  and  nitrates.  It  is  the 
latter  that  form  the  nitrogen  food  of  the  plant.  Much  can 
be  done  in  practice  to  improve  the  rate  at  which  nitrifica- 
tion proceeds.  In  calcareous  soils  the  nitrification  proceeds 
at  a  much  greater  rate  than  in  soils  deficient  in  lime.  Clays 
can  be  made  to  nitrify  much  faster  if  they  are  opened  up 
so  that  they  admit  air.  The  chief  requirements  for  the 
oxidation  of  nitiogenous  matter  in  the  soil  are  air,  warmth, 
moisture,  and  lime.  Tillage  and  bulky  manures  will  supply 
more  air  to  the  soil,  and  control  the  water  supply  as  well. 
L,ime  may  need  to  be  added  directly  to  the  soil.  When 
the  soil  is  closely  packed,  saturated  with  water,  and  air 
excluded,  denitrification  may  occur  (p.  51).  The  fixation 
of  nitrogen  in  the  soil  by  soil  bacteria  is  facilitated  by 
a  good  supply  of  suitable  organic  matter,  such  as  the  straw 
in  farmyard  manure,  phosphatic  manure,  a  good  supply 
of  potash,  and  satisfactory  conditions  for  the  growth  of  the 
bacteria. 

Soils  and  Fertilizers. — The  relationship  between  the  soil 
and  the  fertilizer  used  is  an  important  point  that  must  be  con- 
sidered. To  some  extent  this  has  already  been  discussed  in 
Part  I.  Generally  speaking,  lime  is  a  necessity  for  the  sound 
working  of  any  of  the  fertilizers,  with  the  exception  of  basic  slag 
and  calcium  cyanamide,  which  both  contain  a  certain  amount 
of  lime.  Soils  that  are  very  deficient  in  one  of  the  ingredients 
will  respond  specially  to  that  particular  ingredient  at  first, 
but  it  not  infrequently  occurs  that  as  soon  as  one  has 
satisfied  the  main  need  of  the  soil,  a  second  order  of  necessity 
makes  its  appearance.  There  are  many  soils  whose  chief 
demand  is  phosphate,  and  very  little  good  can  be  done  to 
such  soils  until  phosphates  have  been  supplied.  Afterwards 


SOILS  AND   THEIR  PROPERTIES  83 

potash  and  nitrogen  may  have  their  turn  in  producing 
satisfactory  crops.  In  other  words,  we  go  back  again  to  the 
old  proposition  that  the  soil  requires  a  certain  balance  of 
ingredients,  and,  however  lacking  the  soil  may  have  been 
once  upon  a  time,  in  one  ingredient,  if  you  persist  in  supplying 
this  ingredient  there  may  come  a  time  when  the  chief  necessity 
of  the  soil  is  something  else  altogether.  Much  harm  has 
been  done  in  the  past  by  the  "  rule  of  thumb  "  man  in  this 
respect.  In  the  relatively  early  days  of  agriculture,  manuring 
with  animal  refuse  was  practised  to  a  large  extent.  At 
first  this  process  was  good,  but  it  very  speedily  became  over- 
done ;  then  the  fashion  for  applying  lime  set  in.  At  first 
this  was  very  necessary,  because  it  had  been  neglected  in 
the  past,  but  that,  too,  soon  became  overdone.  Then  a 
fashion  for  the  artificial  manures,  generally  phosphatic 
ones,  set  in  which  have  often  been  exhaustive  of  lime  in 
the  soil.  To-day  the  needs  of  agriculture  in  populous 
countries  are  often  more  connected  with  the  mismanagement 
of  the  past  than  with  any  other  one  factor.  In  taking  up 
land,  therefore,  the  past  agricultural  history  is  always  a 
matter  of  great  importance.  The  analysis  of  the  soil  will 
assist  in  checking  the  history  of  past  good  or  bad  manage- 
ment. 

1 '  The  Law  of  Diminishing  Returns  ' '  is  now  a  recog- 
nized principle.  When  a  manure  is  applied  in  increasing 
quantities  it  does  not  produce  a  corresponding  increase  of  each 
additional  amount  of  manure.  The  table  on  p.  84,  gives  the 
standard  illustration  from  Rothamsted,  in  which  it  will  be 
noted  that  a  steady  increase  in  the  amounts  of  ammonia 
compounds  soon  becomes  unprofitable. 

Whether  a  particular  increase  of  crop  obtained  from  a 
particular  quantity  of  manure  is,  or  is  not,  profitable,  depends 
upon  the  prices  of  both.  Whilst  in  the  above  table  89 
bushels  of  wheat  per  acre  may  be  a  profitable  return  for 
200  pounds  of  ammonium  salts,  yet  if  the  ammonia  became 
cheap  and  the  wheat  dear,  the  4-5  bushels  of  wheat  as 
returned  from  200  pounds  of  ammonium  salts  might  also  be 
very  profitable.  In  other  words,  intensive  cultivation  which 


84 


PLANT  PRODUCTS 


TABLE  14. — CROP  YIELDS  WITH  INCREASING  NITROGEN  SUPPLY, 
ROTHAMSTED. 


Wheat  grain. 

Wheat  straw. 

Bushels  per  acre. 

Cwt.  per  acre.     . 

Increase  per 

Increase  per 

200  Ibs.  am- 

200 Ibs.  am- 

monium salts. 

monium  salts. 

Mineral  manure  alone  per  acre  .  . 

T4'5 

_ 

I2'I 



Mineral  manure  +200  Ibs.  ammo- 

nium salts  per  acre 

23-2 

87 

2I-4 

9'3 

Mineral  manure  +400  Ibs.  ammo- 

nium salts  per  acre 

32-1 

3-9 

32-9 

"*5 

Mineral  manure  +600  Ibs.  ammo- 

nium salts  per  acre 

36-6 

4'5 

4ri 

8'2 

is  profitable  when  prices  of  produce  are  high  becomes 
unprofitable  when  prices  are  low.  Doubtless  if  every  user  of 
artificial  fertilizers  were  to  start  using  artificial  fertilizers 
in  double  quantities  because  the  rise  in  agricultural  produce 
justifies  such  a  procedure,  then  the  prices  of  the  agricultural 
fertilizers  would  rise  so  high  as  to  put  a  stop  to  their  economic 
use.  Exactly  where  the  dividing  line  between  what  is 
practicable  and  what  is  not  must  be  determined  in  every 
case  by  the  cultivator  of  the  soil  himself. 


REFERENCES  TO  SECTION  I 

Leake,  "  Some  Preliminary  Notes  on  the  Physical  Properties  of  the 
Soils  of  the  Ganges  Valley,  more  especially  in  their  Relation  to  Soil  Moisture," 
Journ.  Agric.  Science,  i.,  p.  454. 

Keen,  "  The  Evaporation  of  Water  from  the  Soil,"  Journ.  Agric.  Science, 
vi.,  p.  456. 

Luxmore,  "  The  Soils  of  Dorset,"  pp.  7,  n. 

Russell,  "  Soil  Conditions,"  pp.  75,  87.     (Ixmgmans.) 

Hilgard,  "  Soils,"  pp.  83,  107.     (Macmillan.) 

Hall,  "  The  Soil,"  pp.  48,  154.     (Murray.) 

Fream,  "  Soils  and  their  Properties."     (Bell.) 

Warrington,  "  Physical  Properties  of  Soils."     (Clarendon  Press.) 

Tempany,  "  The  Shrinkage  of  Soils,"  Journ.  Agric.  Science,  viii., 
p.  312. 

Balls,  "  The  Movements  of  Soil  Water  in  an  Egyptian  Cotton  Field," 
Journ.  Agric.  Science,  v.,  p.  469. 

Alvvay,  "  Studies  of  Soil  Moisture  in  the  '  Great  Plains  '  Region,"  Journ. 
Agric.  Science,  ii.,  p.  333. 

Leather,  "  Memoirs  of  the  Department  of  Agriculture  in  India,"  Feb., 
1908,  p.  79  ;  July,  1907,  p.  49;  April,  1906,  p.  3  ;  and  Feb.,  1900,  p.  125, 
(The  Imperial  Department  of  Agriculture  in  India.) 


SOILS  AND   THEIR  PROPERTIES  85 

Leather,  "  The  Agricultural  Ledger,"  1898,  No.  2,  p.  22.  "  The  Water 
of  the  Soil,"  p.  10.  (Government  Printing  Office,  India.) 

Hall  and  Miller,  "  The  Effect  of  Plant  Growth  and  of  Manures  upon 
the  Retention  of  Bases  by  the  Soil,"  Proc.  Royal  Soc.,  B,  vol.  77,  1905,  p.  30. 

Hall,  Brenchley,  and  Underwood,  "  The  Soil  Solution  and  the  Mineral 
Constituents  of  the  Soil,"  Journ.  Agric.  Science,  vi.,  p.  278. 

Collins,  "  Scheibler's  Apparatus  for  the  Determination  of  Carbonic 
Acid  in  Carbonates,"  Journ.  Soc.  Chem.  Ind.,  1906,  p.  518. 

Collins,  "  Agricultural  Chemistry  for  Indian  Students,"  p.  44.  (Govern- 
ment Printing  Office,  Calcutta.) 

Russell  and  Appleyard,  "  The  Atmosphere  of  the  Soil ;  its  Composition 
and  the  Causes  of  Variation,"  Journ.  Agric.  Science,  vii.,  i. 

Schreiner,  Journ  Phys.  Chem.,  1906,  p.  258. 

Dyer,  "  A  Chemical  Study  of  the  Phosphoric  Acid  and  Potash  Contents 
of  the  Wheat  Soils  of  Broadbalk  Field,  Rothamsted,"  Proc.  Roy.  Soc.,  1907, 
p.  ii. 

Miller,  "  The  Amount  and  Composition  of  the  Drainage  through  Un- 
manured  and  Uncropped  Land,  Barnfield,  Rothamsted,"  Journ.  Agric. 
Science,  i.,  p.  377. 

Russell,  "  Washing-out  of  Nitrate  from  Arable  Soil  during  Past  (1915-16) 
Winter,"  Journ.  Board  of  Agriculture,  1916-17,  p.  22. 

Lawes  and  Gilbert,  "  The  Rothamsted  Experiments." 

Gilchrist,  "  Guide  to  Experiments,"  1917.     (Ward,  Newcastle.) 

Hall  and  Amos,  "The  Determination  of  Available  Plant  Food," 
Journ.  Chem.  Soc.,  1906,  T.  205. 


SECTION  II.— SPECIAL  SOIL  IMPROVERS 

Lime. — The  exact  dividing  line  between  what  constitutes  a 
fertilizer  and  what  constitutes  a  soil  improver  is  rather  diffi- 
cult to  determine,  but  whilst  farmyard  manure  is  commonly 
considered  a  fertilizer,  since  it  contains  nitrogen  and  potash, 
yet  lime  is  usually  looked  upon  from  a  different  point  of  view. 
The  lime  is  applied  to  the  soil  for  the  purpose  of  modifying 
the  soil.  The  standard  article  is  quicklime,  produced  by 
burning  limestone.  This  is  sometimes  applied  in  big  lumps, 
called  shell  lime,  but  it  is  much  better  reduced  to  powder, 
either  by  actual  grinding,  or  by  slacking  with  water,  when 
it  crumbles  down.  A  high  quality  burnt  lime  will  contain 
from  90  to  95  per  cent,  of  lime,  and  this  type  of  lime  should 
always  be  used  for  agricultural  purposes.  A  low  quality 
lime,  such  as  the  following  : — 

TABLE  15. 

Lime  . .          . .          . .          . .          . .          . .     45  per  cent. 

Magnesia    ..          ..          ..          ..          ..          ..23 

Carbonic  Acid        ..          ..          ..          ..          ••     £4 

Water -'2 

Silica  ..          ..          ..          ..          ..          ..ii 

Oxides  of  Iron  and  Aluminium  . .          . .         . .     16 

is  of  no  use  for  agricultural  purposes.  I/ime  is  sometimes 
employed  to  increase  the  ratio  of  lime  to  magnesia,  for  which 
purpose  the  lime  in  Table  15  is  very  nearly  useless.  L,ime, 
like  other  materials,  should  be  distributed  as  evenly  as 
possible,  although  this  may  not  be  quite  so  critical  a  point 
as  it  is  in  other  fertilizers.  One  of  the  purposes  for  which 
lime  is  necessary  in  a  soil  is  to  assist  nitrification.  Calcium 
bi-carbonate  in  solution  will  rise  and  fall  in  the  soil,  according 
to  the  dry  or  wet  weather,  though  it  will  not  diffuse  laterally. 


SPECIAL  SOIL  IMPROVERS  87 

Nitrification  will,  therefore,  proceed  either  above  or  below 
a  lump  of  lime  material,  but  it  is  much  better  to  get  a  small 
dressing  well  distributed  than  to  depend  upon  haphazard 
heavy  dressing.  The  lime,  as  soon  as  it  is  applied  to  the 
soil,  combines  with  water  and  forms  calcium  hydrate,  and  then 
absorbs  carbonic  acid,  forming  calcium  carbonate.  lyime 
also  enters  into  combination,  at  any  rate  in  a  temporary 
manner,  with  the  organic  matter  and  clay.  The  addition 
of  lime  to  a  soil  increases  the  amount  of  available  potash 
and  available  nitrogen.  It  does  not  increase  the  amount 
of  available  phosphorus,  excepting  in  the  case  of  soils 
containing  much  organic  matter,  where  a  considerable 
fraction  of  the  total  amount  of  phosphorus  in  the  soil  is 
in  some  form  of  organic  combination.  L,ime,  when  turned 
into  calcium  bi-carbonate,  coagulates  clay,  and  opens  up 
nearly  all  types  of  soil.  It  is,  therefore,  particularly  suitable 
for  the  heavier  types  of  land.  As  it  tends  to  dry  out  clay 
soils,  lime  should  be  applied  fairly  early,  otherwise  the  soil 
may  be  too  dry  for  satisfactory  germination  of  the  seeds, 
lyime  is  especially  necessary  with  high  farming.  Super- 
phosphates, sulphate  of  ammonia,  nitrate  of  soda,kainit,  farm- 
yard manure  and  organic  nitrogen  manures  all  demand  lime 
in  the  soil.  There  are  a  great  many  forms  of  industrial  waste 
lime  which  can  be  used,  the  relative  values  of  which  depend 
upon  the  amount  of  calcium  contained.  When  limestone  is 
burned  it  loses  about  40  per  cent,  of  its  weight,  and  the  subse- 
quent cost  of  carriage  is  that  much  less.  It  may  be  cheaper 
to  burn  coal  in  the  lime  kiln,  and  thus  to  reduce  the  weight, 
than  to  burn  coal  in  a  steam  engine  for  the  purpose  of  carrying 
useless  carbonic  acid.  These  varied  forms  of  calcium  car- 
bonate can  only  be  considered  it  they  are  relatively  cheap. 
Very  considerable  quantities  of  waste  lime  are  produced  in 
the  "lyeblanc  "  soda  process.  Calcium  sulphide  obtained  as 
a  by-product  is  treated  with  carbon  dioxide  in  water  with 
the  evolution  of  hydrogen  sulphide,  then  used  for  manufacture 
of  sulphur.  The  waste  calcium  carbonate  is  run  into  heaps 
and  allowed  to  dry  spontaneously.  This  material,  often 
called  "  Chance  "  mud,  or  lime  mud,  has  proved  a  perfect 


88  PLANT  PRODUCTS 

substitute  for  lime,  but  it  does  not  contain  more  than  about 
40  per  cent,  pure  lime  and  has  to  compete  with  lime  of  90 
to  95  per  cent,  purity  in  the  case  of  burnt  lime.  It  is  not 
possible  to  convey  it  by  rail  any  considerable  distance,  as 
the  railway  freight  soon  swallows  up  any  advantage  of  low 
price.  In  spite  of  the  fact  that  the  "  Chance  "  mud  is  a 
fine  precipitate,  it  runs  together  in  lumps  in  the  soil  and  is  as 
difficult  to  distribute  as  shell  lime.  Lumps  of  "  Chance  " 
mud  can  be  found  in  a  soil  many  years  after  application. 
Another  residue  of  a  similar  type  is  produced  from  magnesian 
limestone  by  the  extraction  of  the  magnesia  for  industrial 
purposes.  The  waste  is  very  similar  to  "  Chance  "  mud, 
as  the  amount  of  magnesia  not  extracted  is  very  small. 
Where  chalk  is  obtainable,  treating  soils  with  chalk  is  a  well- 
known  process.  Even  when  the  soils  lie  on  the  top  of  the 
chalk,  the  surface  sometimes  contains  but  little  lime.  Chalk 
pits  are  dug  in  the  fields,  and  the  chalk  then  distributed  on 
the  surface.  Building  mortar  can  also  be  employed  as  a 
source  of  lime.  The  residue  of  acetylene  gas-plants  provides 
a  very  pure  source  of  calcium  hydrate.  In  a  very  crude 
form  one  may  find  lime  from  skin  dressers  and  many  small 
industries. 

The  effect  of  gas  lime  depends  on  sulphur  and  cyanogen  far 
more  than  upon  the  amount  of  lime  contained.  Fresh  gas 
lime  contains  considerable  quantities  of  calcium  sulphide, 
which  oxidizes  on  keeping  to  calcium  sulphite.  Up  to  that 
stage  oxidation  is  rapid,  but  the  further  oxidation  of  calcium 
sulphite  to  sulphate  in  a  heap  of  gas  lime  is  slow,  although 
once  it  has  been  distributed  in  the  soil  the  action  is  moder- 
ately rapid.  In  addition  there  are  sulpho-cyanides,  ferro- 
cyanides,  and  sometimes  cyanides  themselves.  These  are  all 
poisonous  bodies,  and  hence  the  action  of  gas  lime  depends  on 
partial  sterilization  (p.  90).  Gas  lime  contains  about  30  or  40 
per  cent,  of  calcium  carbonate,  and  when  the  other  substances 
have  had  time  to  decompose,  this  material  produces  its 
effects.  A  most  important  lime  compound  with  very  different 
properties  is  gypsum  (hydrated  calcium  sulphate.)  This 
has  no  practical  resemblance  to  burnt  lime,  and  its  action 


SPECIAL  SOIL  IMPROVERS  89 

on  the  soil  is  totally  dissimilar.  The  great  advantages 
of  gypsum  lie  (i)  in  the  fact  that  it  is  a  sulphur  compound, 
and  sulphur  is  necessary  for  the  formation  of  proteins  ; 
(2)  that  it  decomposes  sodium  carbonate  in  the  soil,  and 
coagulates  colloidal  clay  better  than  any  other  substance. 
When  clay  has  been  puddled  by  excessive  application  of 
nitrate  of  soda,  and  injudicious  working  in  wet  weather, 
calcium  sulphate  is  an  admirable  cure.  At  one  time  plastering 
soils  was  a  well-known  process,  much  recommended  for  the 
growth  of  clovers.  It  has  gone  out  of  fashion  in  the  British 
Isles,  but  the  use  of  gypsum  is  still  important  in  many  parts 
of  the  world,  and  the  experience  of  the  British  Isles  must  not 
be  taken  to  apply  everywhere.  The  reason  why  gypsum 
has  gone  out  of  fashion  to  such  a  large  extent  is  that  calcium 
sulphate  is  applied  to  the  soil  with  other  materials.  Super- 
phosphates contain  more  than  half  their  weight  of  calcium 
sulphate.  Soils,  therefore,  that  have  been  liberally  treated 
with  super-phosphate  are  likely  to  be  overcharged  with 
calcium  sulphate.  Sulphate  of  ammonia  applied  in  one 
year  of  a  rotation,  and  lime  applied  in  another,  will  produce 
calcium  sulphate  in  the  soil.  Owing  to  the  powerful  action 
of  gypsum  it  is  still  much  believed  in  by  some  horticulturists, 
whose  duties  are  often  to  break  up  very  unsatisfactory  land 
and  grow  crops  with  as  little  delay  as  possible.  Hills 
composed  of  little  but  gypsum  occur  in  some  parts  of  the 
world,  and  as  it  is  mined  very  easily,  such  local  deposits 
of  gypsum  should  always  be  carefully  considered  by  those 
cultivating  land  at  no  great  distance. 

In  the  vicinity  of  large  towns  sulphur  in  the  form  of 
sulphuric  acid  is  brought  down  by  the  rain  with  the  subsequent 
formation  of  gypsum  in  the  soil.  On  the  whole  gypsum 
reacts  with  the  soil  as  an  acid  whilst  lime  reacts  as  an 
alkali. 

The  Use  of  Electricity  in  Plant  Stimulation. —This 
subject  has  attracted  much  attention  for  many  years  past. 
It  is  such  an  obvious  idea  that  the  original  suggesters  are 
probably  many  in  number,  but  one  of  the  foremost  workers 
in  the  first  days  of  any  substantial  results  was  Professor 


90  PLANT  PRODUCTS 

I/emstrom.  He  succeeded  by  using  electricity  at  a  high 
tension  conveyed  by  wires  over  a  field.  He  employed  an 
ordinary  town  current  to  drive  a  small  electric  motor, 
driving  in  its  turn  a  small  influence  static  electric  machine. 
Subsequently  the  work  was  taken  up  by  Professor  Priestley 
at  Bristol  and  I^eeds.  The  method  now  adopted  is  to  use 
a  transformer  with  a  rectifier  to  give  positive  electricity 
at  a  high  tension.  The  details  have  by  no  means  yet  been 
worked  out.  But  the  latest  ideas  suggest  that  wires  are 
best  distributed  overhead  at  about  five  feet  in  height,  and 
that  the  wires  should  be  made  as  thin  as  possible.  Under 
these  conditions  a  very  marked  increase  in  crops  has  been 
obtained.  The  actual  cost  of  the  electric  energy  is  quite 
small,  but  the  initial  expense  of  the  machinery  is  considerable, 
and  at  present  requires  skilled  attention.  Until  details 
have  been  worked  out  on  the  large  experimental  scale,  it 
will  be  difficult  to  make  a  commercial  success  of  this  method. 
Many  points  remain  yet  to  be  discovered,  such  as  the  relation- 
ship of  light  and  varying  humidity  of  the  air,  the  strength 
of  the  discharge,  and  the  relationship  between  electrification 
and  the  manure  used.  All  these  points  require  to  be  investi- 
gated thoroughly.  The  great  advance,  however,  which  has 
been  made  since  I/emstrom's  days  by  Priestley,  Jorgensen, 
and  Blackwood  promises  future  progress. 

The  Partial  Sterilization  of  Soils.— It  is  a  very  old, 
well-known  fact  that  the  application  of  heat,  and  all  kinds  of 
poisonous  substances  to  soils,  may  increase  the  ultimate  crop 
obtained,  even  though  some  injury  may  occur  at  the  moment. 
From  the  elementary  cottage  idea  of  putting  a  flower-pot  into 
the  oven  for  a  short  time,  up  to  the  laboratory  researches  of 
Dr.  Russell,  the  subject  of  application  of  heat  to  a  soil  has 
been  freely  discussed.  In  nature  this  process  occurs  in  hot 
climates  where  solar  radiation  may  raise  the  surface  tempera- 
ture of  the  soil  up  to  60°  Cent.  (140°  Fahr.).  Under  these 
conditions  many  pests  in  the  soil  are  destroyed,  so  that  the 
ultimate  growth  of  the  crop  is  improved.  In  greenhouses 
steam  is  not  infrequently  employed  for  the  purpose  of  heating 
the  soil  on  a  moderately  large  scale.  In  a  similar  way  all 


SPECIAL  SOIL  IMPROVERS  91 

germicides  of  a  mild  character,  such  as  naphthalene,  and  even 
copper  sulphate,  and  zinc  sulphate,  have  been  used  with 
ultimately    satisfactory    results.     Recent    researches    have 
shown  that  this  treatment  involves  the  destruction  of  all 
kinds  of  harmful  organisms,  from  wireworms  or  millipedes, 
down  to   microscopic   forms   like  the  amoebae,  paramecia, 
etc.,  the  larger  of  which  directly  injure  the  plant,  and  the 
smaller   of   which   destroy   the   useful   nitrifying   bacteria. 
The  destruction  of  pests  soon  produces  an  improvement 
in  the  crop,  whilst  the  destruction  of  the  enemies  of  the 
nitrifying  bacteria  results    in  an  increased  production  of 
nitrate,  with  a    subsequent  increased  production  of  plant 
growth.     Heat  also  produces  chemical  and  physical  changes 
in  the  soil.     The  apparent  results  of  heating  the  soil  with 
steam  are  very  similar  to  those  of  the  action  of  frost — the 
soil  becomes  lighter,  easier  to  work,  easier  for  the  plant  to 
establish  its  roots,  richer  in  soluble  mineral  matter,  and  the 
organic  matter  is  more  easily  converted  into  ammonia  and 
nitrates  by  the   organisms   in  the   soil.     The   application 
of  heat  is  certainly  the  most  efficient  of  these  methods,  but 
is  not  very  easy  to  conduct  on  a  large  scale.     Direct  baking 
is  probably  one  of  the  best   methods,  but  steam  heating 
is  also  very  satisfactory.     The  application  of  germicides  is 
so  much  easier  to  carry  out  that  it  has  attracted  a  great 
deal  of  attention.     Gas  lime,  the  waste  product  from  purifi- 
cation of  coal  gas,  contains  sulpho-cyanides,  ferro-cyanides, 
and  other  poisonous  substances.     Occasionally,  when  the 
gas  lime  has  been  applied  to  pasture,  the  iron  in  the  green 
grass  is  turned  to  Prussian  blue,  owing  to  the  action  of  the 
cyanogen  compounds  in  the  gas  lime.     The  sulphides  and 
sulphites  in  the  gas  lime  no  doubt  also  play  their  part  in 
acting  upon  all  forms  of  soil  pests.     After  the  sulphides  and 
sulphites   and   cyanogen   compounds   have   been   oxidized, 
the  residue  acts  as  a  fertilizer.     Calcium  carbide  has  also 
been  used.     Naphthalene  is  another  favourite  soil  fumigant. 
Crude  naphthalene  is  a  fairly  cheap  article,  and  not  difficult 
to  distribute.     It  is  mixed  with  coke  dust,  gas  lime,  or  ashes, 
for  the  production  of  many  patent  mixtures,  which  usually 


92  PLANT  PRODUCTS 

contain  about  30  to  50  per  cent,  of  crude  naphthalene.  These 
mixtures  are  rather  drier,  and  more  convenient  to  handle. 

Soot  may  be  considered  to  have  a  value  partly  dependent 
on  tar  and  other  poisonous  materials. 

There  is  considerable  reason  for  supposing  that  many  of 
these  poisonous  substances  do  some  slight  injury  to  the  crop, 
but  if  the  destruction  of  wire  worms,  etc.,  is  on  a  sufficiently 
large  scale,  the  subsequent  benefit  will  more  than  compensate 
for  the  temporary  injury.  It  is  desirable  that  all  these 
substances  should  be  applied  to  the  soil  at  a  considerable 
interval  of  time  before  sowing  seeds.  If  that  is  not  practic- 
able some  slight  good  may  perhaps  be  done  by  applying  such 
germicides  between  the  drills,  so  as  to  keep  as  far  away  from 
the  plant  as  possible,  but  this  latter  practice  must  be 
considered  as  open  to  some  objections.  Injudicious  use  of 
soil  fumigants  has  done  much  harm. 

REFERENCES  TO   SECTION   II 

Russell,  "  Chalking :  A  Useful  Improvement  for  Clays  overlying  the 
Chalk,"  Journ.  Board  of  Agriculture,  1916-17,  p.  625. 

Hutchinson  and  Maclennan,  "  Studies  on  the  Lime  Requirements  of 
Certain  Soils,"  Journ.  Agric.  Science,  vii.,  p.  75. 

Collins,  "  Scheibler's  Apparatus  for  the  Determination  of  Carbonic 
Acid  in  Carbonates,"  Journ.  Soc.  Chem.  Ind.,  1906,  p.  518. 

Roscoe  and  Schorlemmer,  vol.  ii.,  p.  290. 

Lemstrom,  "  Electricity  in  Agriculture  and  Horticulture." 

Jorgensen  and  Priestley,  "  The  Distribution  of  the  Overhead  Electrical 
Discharge  employed  in  Recent  Agricultural  Experiments,"  Journ.  Agric. 
Science,  vi.,  p.  337. 

Blackman  and  Jorgensen,  "  The  Overhead  Electric  Discharge  and  Crop 
Production,"  Journ.  Board  of  Agriculture,  1917-18,  p.  45. 

Russell  and  Petherbridge,  "Investigations  on  'Sickness'  in  Soil," 
Journ.  Agric.  Science,  October,  1913.  Russell,  "Partial  Sterilization  of 
Soil  for  Glasshouse  Work,"  Journ.  Board  of  Agriculture,  1911-12,  p.  809; 
1912-13,  p.  809;  1914-15,  p.  97. 

Russell  and  Hutchinson,  "  The  Effect  of  Partial  Sterilization  of  Soil  on 
the  Production  of  Plant  Food,"  Journ.  Agric.  Science,  October,  1909. 

Buddin,  "  Partial  Sterilization  of  Soil  by  Volatile  and  Non- Volatile 
Antiseptics,"  Journ.  Agric.  Science,  vi.,  p.  417. 

Russell,  "  Soil  Conditions,"  p.  114.     (Longmans,  Green.) 

Wentworth,  "Effect  of  Electricity  on  Sheep  Raising,"  Journ.  Board 
of  Agriculture,  1911-12,  p.  519. 

Brenchley,  "  Inorganic  Plant  Poisons."     (Camb.  Univ.  Press.) 

Hanley,  "Lime  and  the  Liming  of  Soils,"  Journ.  Soc.  Chem.  Ind., 
1918,  p.  185  T. 


SECTION  III.— SOIL  RECLAMATION  AND 
IMPROVEMENT 


Barrenness. — Very  large  numbers  of  soils  are  not 
producing  anything  approaching  to  their  maximum  crop, 
although  one  cannot  definitely  classify  them  as  being  under 
the  well-recognized  types  of  land  difficult  of  cultivation. 
These  lands  are  only  partially  barren,  from  improper  treat- 
ment due  frequently  to  economic  causes. 

The  supply  of  plant  food  in  the  soil  is  sometimes  the 
chief  cause  for  the  difference  between  productive  and 
unproductive  land.  Table  16  shows  the  amount  of  plant 
food  in  productive  and  unproductive  types  of  soil. 

TABLE  16. — COMPOSITION  OF  SOILS. 
Parts  per  Two  Million  or  Pounds  per  Acre  to  a  Depth  of  Seven  Inches. 


Elements  of  plant  food. 

Very  productive  soils. 

Non-productive  soils. 

Holland 
alluvium. 

Scotland 
wheat  soil. 

German 
barrens. 

Maryland 
barrens. 

Phosphorus 
Potassium 
Calcium     .. 

4,100 
17,040 
58,460 

3>78o 
5,880 
17.560 

trace 
none 
1380 

1  80 
2000 
580 

A  very  common  cause  of  unproductiveness  in  a  soil  is  the 
lack  of  proper  plant  food.  There  are  many  other  causes, 
but  there  are  few  of  them  quite  so  common  as  the  question 
of  the  supply  of  proper  mineral  plant  food  in  the  soil.  That 
the  supply  of  plant  food  in  the  soil  is  a  very  fundamental 
question  is  illustrated  in  Table  17,  which  shows  the  relative 
supply  and  demand  of  the  most  important  elements  of  plant 
food,  and  it  will  be  noted  on  purely  fundamental  grounds 


94 


PLANT  PRODUCTS 


that  the  total  amount  of  phosphate  in  the  crust  of  the  earth 
is  not  super-abundant  for  the  purpose  of  wheat  production. 

TABLE  17. — RELATIVE  SUPPLY  AND   DEMAND  OF  ELEMENTS   IN 
EARTH  AND  PLANTS. 


Essential  plant-food  elements. 

Pounds  in  2  million 
of  the  average  crust 
of  the  earth. 
=  i  acre  to  7"  depth. 

Pounds  in  40 
bushels  of  wheat 
and  straw. 

Number  of 
years'  supply 
indicated. 

Phosphorus 

2,200                              13 

170 

Potassium 

49,2OO                              30 

1,  600 

Calcium 

68,800                          9 

55,00o 

Nitrogen  in  air 

70  million  Ibs. 

70 

1,000,000 

over  one  acre. 

There  are  many  districts  in  the  world  which  we  know  have 
been  cultivated  for  at  least  a  few  thousand  years,  but  the 
amount  of  phosphorus  in  the  earth's  crust,  as  shown  in  this 
table,  would  only  justify  us  in  the  conclusion  that  we  could 
grow  bumper  crops  lor  170  years.  A  commonly  occurring 
deficiency  of  phosphorus  is,  therefore,  to  be  anticipated. 
The  other  causes  besides  the  lack  of  plant  food  are  excess 
or  deficiency  of  moisture,  indifferent  physical  condition, 
absence  of  beneficial  or  presence  of  harmful  soil  organisms,  or 
the  presence  of  some  substances  injurious  to  plant  life.  In 
sandy  soils  the  lack  of  colloids  is  so  detrimental  that  almost 
complete  sterility  may  occur.  The  ordinary  sand  on  the 
sea-shore,  for  example,  is  very  barren,  owing  to  the  action 
of  the  sea  water  having  washed  out  all  colloidal  material. 
A  few  struggling  plants  may  manage  to  make  themselves 
at  home,  and  gradually  add  a  certain  amount  of  humus  to 
the  soil,  after  which  the  general  growth  of  plants  may 
begin. 

Dry  Lands. — I/and  that  is  too  dry  and  has  too  little 
natural  water  is  one  that  requires  some  system  of  irrigation 
to  be  thoroughly  satisfactory.  Irrigation  generally  has  to  be 
obtained  by  some  reservoir  system  of  water  supply.  Where 
large  rivers  are  obtainable,  as  in  the  northern  parfc  of  India, 
and  in  the  case  of  the  Nile  Valley,  dams  can  be  placed  across 
the  rivers.  On  dry  lands  shallow  tillage  is  essential.  For 


SOIL  RECLAMATION  AND  IMPROVEMENT    95 

this  purpose  the  most  suitable  source  in  dry  climates  is  a 
river  which  can  be  relied  upon  to  run  in  dry  weather.  Such 
are,  however,  scarce,  and  are  chiefly  to  be  found  in  rivers 
that  travel  from  long  distances,  or  originate  in  snow  moun- 
tains. The  rivers  originating  in  the  Himalayas  are  specially 
suitable  for  this  purpose,  since  the  melting  of  the  snows  in 
the  summer  gives  ample  supplies  of  water.  The  Nile,  rising 
a  great  distance  away,  gives  a  flow  of  water  at  the  right  time. 
The  erection  of  dams  or  barrages  across  the  river  will  hold 
the  water  up,  and  divert  it  into  proper  channels,  which  then 
communicate  with  distributing  channels  of  smaller  size. 
The  supply  of  water  by  these  means  depends  upon  the 
organization  of  distribution.  In  Madras,  and  many  parts 
of  India,  very  old-established  tanks  occur,  which  have  been 
originally  produced  by  the  utilization  of  some  natural 
depression  by  building  a  dam  across  the  original  outlet.  The 
rainfall  is  collected  from  a  small  area,  but  the  natives  collect 
considerable  quantities  of  water  in  the  rainy  season,  and 
utilize  it  in  the  dry  season.  When  the  water  from  such 
tanks  has  been  let  out,  the  wet,  muddy  bottom  is  used  for 
cultivation  of  rice.  From  such  large,  open  tanks  the  loss 
of  water  by  evaporation  is  very  considerable.  The  expense 
of  instituting  such  a  system  would  be  very  heavy,  but  nearly 
all  these  somewhat  primitive  arrangements  have  been 
produced  by  degrees,  mostly  utilizing  labour  which  would 
otherwise  have  been  wasted.  The  water  is  applied  to  such 
dry  lands  by  running  the  water  along  channels,  the  distance 
between  which  will  depend  upon  the  type  of  crop  grown. 
There  is  a  great  tendency  on  the  part  of  the  users  to  take 
more  than  is  necessary.  Deep  ploughing  only  lets  the 
water  of  the  subsoil  evaporate.  Mulches  should  be  used  as 
much  as  possible.  Many  soluble  manures,  especially  phos- 
phates, economize  water.  Nitrogenous  manures,  such  as 
sulphate  of  ammonia,  if  applied  when  the  plant  is  suffering 
from  drought,  may  often  increase  the  crop. 

Wet  Lands. — Wet  lands  require,  as  a  rule,  drainage. 
Drains  should  be  set  not  too  deep,  and  should  lead  without 
any  very  sharp  angles  into  the  main  drain.  By  such  a 


96  PLANT  PRODUCTS 

system  of  drainage  not  merely  is  the  water  removed,  but 
also  air  is  let  into  the  soil.  In  certain  particular  cases,  as, 
for  example,  some  of  the  fens,  the  soil  may  be  alternately 
wet  and  dry.  In  these  fen  districts  it  is  not  uncommon 
that  the  level  of  the  rivers  and  canals  exceeds  that  of  the 
fields.  In  this  particular  case  a  ditch  is  dug  between  the 
field  and  the  river.  The  level  of  this  is  below  the  level 
of  the  field,  and  considerably  below  the  level  of  the  river. 
Into  this  main  ditch  branch  channels  run  to  carry  the  surplus 
water,  which  is  pumped  into  the  river  at  a  higher  level. 
When  dry  weather  intervenes,  it  is  only  necessary  to  reverse 
the  action  of  the  pumps,  and  let  the  water  run  back  into  the 
ditch  from  the  river,  and  thence  into  communicating  channels. 
Very  large  quantities  of  rank  grass  may  be  obtained  by  such 
a  method.  Many  of  the  grasses  which  normally  have  a 
very  bad  name  owe  their  lack  of  nutriment  to  a  big  develop- 
ment of  fibrous  stalk.  Under  conditions  of  perpetual 
moisture  these  grasses  never  mature,  and  are,  therefore, 
always  moderately  succulent. 

One  of  the  results  of  bad  drainage  in  a  soil  is  a  tendency 
to  accumulate  poisonous  materials.  When  the  clay  con- 
stituents of  a  soil  contain  large  amounts  of  soda,  the  soda 
is  removed  from  the  clay  by  the  action  of  water  containing 
carbonic  acid,  producing  sodium  carbonate,  which  defloccu- 
lates  the  soil.  One  of  the  cures  for  this  is  drainage  which 
removes  the  soda  salts.  The  application  of  gypsum  to  such 
a  soil  converts  the  sodium  carbonate  into  sodium  sulphate 
which  washes  away  with  rain,  and  leaves  calcium  carbonate 
behind.  The  former  is  relatively  harmless  and  drains 
away  in  time,  the  latter  is  beneficial.  Sodium  sulphate 
does  not  hinder  the  germination  of  seeds  as  much  as  sodium 
chloride  or  sodium  carbonate.  This  type  of  land  is  known 
in  America  as  the  black  alkali  land,  whilst  in  India  it  is 
known  as  reh  or  usar.  As  on  many  poor  soils,  persistent 
efforts  at  cultivation  result  in  improvement.  Where  the 
land  has  been  steadily  cultivated,  maintained  in  an  open 
condition,  and  ample  plant  food  given,  the  soil  remains 
fertile.  Soils  in  the  vicinity  of  rivers  may  need  reclamation. 


SOIL   RECLAMATION  AND  IMPROVEMENT    97 

Peat. — Peat  is  a  very  infertile  type  of  soil,  but  by  treat- 
ment with  lime  and  basic  slag,  very  fine  results  may  be 
obtained.  Where  a  soil  merely  has  a  thin  layer  of  partly 
peat-like  turf,  mechanical  breaking  up  of  the  surface  will 
often  effect  a  remarkable  improvement.  Heavy  dressings 
of  gas  lime  have  also  proved  beneficial  for  such  purposes, 
but  where  the  peat  is  fairly  deep,  continuous  work  is  necessary 
to  reclaim  it.  Peat  lands  are  often  very  wet,  and  require 
some  system  of  drainage.  Experience  in  Ireland  has 
shown  that  these  soils  are  not  so  hopeless  as  they  were  once 
thought  to  be.  Dressings  of  potash  manures  are  also  very 
commonly  required  for  this  type  of  land.  In  some  cases 
the  process  of  paring  and  burning  may  be  employed  on  peat 
lands.  This  is  very  drastic,  and  wasteful,  but  is  sometimes 
the  most  easily  managed.  The  rab  cultivation  of  the 
Western  Ghats  belongs  to  this  type.  On  many  of  the  fen 
districts  the  application  of  marl,  that  is,  chalky  clay,  has  been 
found  to  be  very  beneficial,  since  it  supplies  lime  in  quantity, 
and  potash  in  small  amounts.  On  peat  lands  liberal  manuring 
with  common  manures  is  almost  always  essential,  since  the 
peat  contains  little  of  any  value  to  the  plant.  It  has, 
however,  always  an  ample  capacity  for  absorbing  water, 
and  its  physical  properties  are,  therefore,  not  excessively 
bad.  Occasionally  peat  may  be  found  already  mixed  with 
lime.  On  such  soils  super-phosphate  will  generally  give  a 
better  result  than  basic  slag.  Whenever  lime  is  applied  to 
soil  for  the  purpose  of  reclaiming  it,  it  is  desirable  that  the 
lime  should  contain  only  a  moderate  portion  of  magnesia, 
since  when  the  percentage  of  magnesia  exceeds  the  percentage 
of  lime,  magnesia  is  harmful. 

Reclamation. — There  are  considerable  areas  of  land 
which  are  only  producing  very  poor  pasture,  which  can 
comparatively  easily  be  made  to  produce  far  better  feeding 
for  stock.  These  areas  occur  in  all  parts  of  the  world,  but 
in  well-populated  districts  there  is  little  excuse  for  their 
existence.  There  are  very  large  areas  of  land  which  have 
merely  been  neglected,  and  which  are  occupied  by  poor 
pasture.  The  boulder  clay  of  the  northern  part  of  England, 

D.  7 


9§  PLANT  PRODUCTS 

as  well  as  other  lands  in  other  parts,  can  be  immensely 
improved  by  dressings  of  basic  slag,  at  the  average  rate  of 
one  or  two  hundredweight  of  slag  per  acre  per  annum. 
Such  treatment  encourages  .the  growth  of  clover,  and  in 
the  course  of  a  few  years  completely  alters  the  physical 
and  chemical  properties  of  the  soil.  Many  uplands,  where 
there  is  much  heather  and  moor,  can  also,  by  a  dressing 
of  slag,  and  possibly  lime,  effect  a  steady  improvement  on 
the  value  of  the  land  by  enclosure  and  stocking  with  cattle. 
Even  some  soils  on  chalk  have  been  reclaimed  in  a  wonderful 
way  by  these  means.  Poverty  Bottom,  the  property  of 
Professor  Somerville,  is  a  case  where  neglected  land  on  chalk 
has  been  immensely  improved  by  the  use  of  basic  slag.  Some 
of  the  lighter  soils  which  are  growing  very  indifferent 
pasture  may  be  made  to  do  much  better  by  the  application 
of  potash,  but,  as  a  rule,  the  lighter  land  should  not  be  down 
to  grass,  but  should  be  ploughed,  unless  there  is  some  specific 
difficulty,  coming  under  the  heading  of  the  wet  lands  alluded 
to  above.  The  reclamation  of  this  type  of  land  ultimately 
involves  considerable  amount  of  capital.  The  amount  of 
money  necessary  to  spend  in  a  substantial  dressing  of  basic 
slag,  probably  assisted  by  lime,  is  one  which  the  farmer  is 
often  afraid  of,  but  by  spreading  it  out  over  several  years 
the  amount  of  money  expended  is  not  so  severely  felt. 
The  difference  between  a  barren  field  and  a  fertile  field  is 
very  often  more  a  matter  of  history  than  geology.  Persistent 
efforts  to  cultivate  a  piece  of  land  and  make  it  fertile  are 
rarely  altogether  unfruitful.  Whether  the  result  justifies 
the  expenditure  of  labour  is,  of  course,  a  different  matter, 
since  it  is  impossible  to  equate  these  two  by  the  same  method 
in  different  epochs.  The  labour  that  would  otherwise  have 
been  wasted  is  not  capable  of  being  put  down  by  any  system 
of  accountancy.  The  gradual  improvement  of  the  land  by 
this  type  of  utilization  of  spare  moments  is  one  of  the  most 
important  results  of  giving  ownership  of  land  to  the  actual 
occupier.  The  man  who  hopes  to  get  results  many  years 
hence  from  his  spare  moments  is  only  the  man  who  thinks 
he  is  likely  to  be  on  the  spot  for  a  long  time.  To  attempt 


SOIL  RECLAMATION  AND  IMPROVEMENT    99 

to  reclaim  many  types  of  land  on  an  industrial  system  is 
very  often  unpromising,  as  the  capital  necessary  to  be  sunk 
is  too  large  in  proportion  to  the  returns.  The  whole  question 
of  reclaiming  land  is  of  little  value  without  considering  some 
system  of  experiment.  The  mere  fact  that  a  piece  of  land 
is  not  doing  well  suggests  the  idea  that  probably  somebody 
has  failed  to  do  better,  and  that  the  case  is,  therefore,  not 
a  simple  one ;  but  it  need  not  necessarily  be  very  compli- 
cated, and  a  simple  type  of  experiment  will  not  infrequently 
solve  the  riddle  as  to  its  failure.  A  soil  is  so  variable  that  if 
any  knowledge  is  required  within  a  reasonable  time,  it  is 
necessary  to  conduct  all  experiments  in  duplicate.  It  is 
not  necessary  that  the  piece  of  land  under  experiment 
should  be  very  large.  The  most  important  consideration 
is  that  the  person  responsible  for  the  experiment  should  have 
a  sound  knowledge  of  the  process  of  conducting  experiments, 
and  a  clear  idea  of  the  errors  of  practical  experiment  under 
practical  conditions.  The  chief  type  of  such  experiment 
would  be  to  lay  out  plots,  of  which  there  were  two  or  three 
plots  containing  no  manure  and  no  improving  treatment 
at  all,  two  or  three  with  phosphates,  two  or  three  with  potash, 
two  or  three  with  nitrogen,  and  two  or  three  with  lime. 
Previous  experience  of  that  type  of  land  would  avoid  many 
unnecessary  experiments,  since  at  least  some  things  might 
be  assumed  fairly  well  beforehand,  but  soils  differ  so  much, 
and  the  causes  of  fertility  and  infertility  are  so  many,  that  it 
does  not  do  to  assume  too  much  from  a  text-book.  Roughly 
speaking,  the  errors  of  experiment  on  a  growing  crop  on  a  piece 
of  land  will  be  about  10  per  cent,  of  the  yield.  For  the  purpose 
of  the  reclamation  of  barren  land  this  is  not  at  all  a  serious 
error,  since  unless  the  land  is  going  to  double  its  capacity 
it  is  hardly  likely  to  pay  any  very  heavy  returns  for  big 
initial  expense.  The  difficulties  are,  therefore,  not  as  great 
as  they  are  on  an  experimental  farm.  As  the  reclamation 
of  land  is  generally  a  matter  of  a  fairly  big  scale,  it  would 
be  especially  foolish  to  neglect  a  few  preliminary  experiments 
before  proceeding  to  effect  some  system  of  reclamation. 
It  is,  of  course,  highly  desirable  that  the  materials  used  for 


ioo  PLANT  PRODUCTS 

the  experiments  should  have  a  fairly  accurately  known 
composition,  as  otherwise  much  ol  the  labour  will  be  thrown 
away.  A  useful  type  of  experiment  would  be,  one  plot 
of  lime,  a  second  plot  basic  slag,  a  third  plot  with  sulphate 
of  ammonia,  a  fourth  plot  with  potash  manure,  and  a  fifth 
plot  with  no  manure  at  all.  These  might  be  all  cross- 
dressed  with  other  manures,  or  even  with  the  same  manures 
applied  over  again.  If  the  same  manures  are  applied  over 
again  in  the  cross-dressing  as  in  the  first  dressing,  one  will 
get,  of  course,  a  double  dressing  in  one  case,  and  a  compound 
dressing  in  another,  but  each  case  will  have  to  depend  upon 
its  own  merits.  The  term  "  reclamation  of  land  "  is  some- 
times restricted  to  warping.  The  process  of  warping  consists 
in  flooding  and  silting  up  swamps.  Where  hill  streams  or 
tidal  estuaries  exist,  the  low-lying  land  can  be  flooded  from 
time  to  time,  and  a  large  quantity  of  silt  deposited.  Such 
silt  is  very  fertile.  No  general  principles  can  be  dictated 
on  this  subject,  it  is  a  question  of  management. 

REFERENCES  TO  SECTION   III 

Leather,  "  Memoirs  of  the  Department  of  Agriculture  in  India,"  June, 

1917.  "The  Pot-Culture  House,"  p.  43.  (Thacker,  Spink  and  Co.,  Calcutta.) 
Hilgard,  "  Soils,"  pp.  399  and  422.     (Macmillan.) 
McConnell,  "  Agricultural  Note  Book,"  p.  81.     (Crosby  Lockwood.) 
Gorham,  "Reclaiming  the  Waste,"  pp.  118,  142.     (Country  Life.) 
Stokes,  "Some  Cases   of    Infertility   in   Peaty   Soils,"   Journ.   Board 

Agriculture,  1913-14,  p.  672. 

"  The  Reclamation  of  Waste  Land,"  Journ.  Board  Agriculture,  1914-15, 

p.  681. 

Howard,  "The  Irrigation  of  Alluvial  Soils,"  Agric.  Journ.  Ind.,  1917, 

p.  185. 

Carey  and  Oliver,  "Tidal  Lands."     (Blackie.) 


PART  III.— THE   CROPS 

SECTION  I.— PHOTO-SYNTHESIS 

THE  natural  absorption  of  solar  energy  by  plants  is  a  process 
called  photo-synthesis,  to  account  for  which  there  are  many 
theories,  none  of  which  can  be  considered  as  proven.  Some 
outstanding  features,  however,  remain  without  any  question. 
The  sun's  rays  falling  upon  green  leaves  are  absorbed  with 
the  utilization  of  energy  for  the  production  of  plant  materials. 
The  proportion  of  energy  used  in  this  way  is  small,  as  is 
shown  in  the  following  table  : — 

TABLE  18. — PERCENTAGE  OF  TOTAL  SOLAR  ENERGY 

FALLING  ON  A  LEAF. 

Energy  used  in  assimilation        . .  . .  . .       0*66  per  cent. 

Energy  used  in  evaporation  of  water  . .  . .     48-39 

Energy  transmitted          ..          ..  ..  ..31*40 

Energy  radiated,  convected,  etc.  ..  ..      19*55        ,, 

This  table  shows  that  the  amount  of  energy  actually  utilized 
for  assimilation  of  carbon  dioxide  and  its  conversion  into 
organic  plant  matter  is  comparatively  small,  and  that  a 
very  great  deal  of  the  energy  is  used  merely  in  evaporating 
water  (see  p.  no).  Carbon  dioxide  is  absorbed  by  the  leaf 
with  very  great  readiness,  in  spite  of  the  small  proportion 
or  carbon  dioxide  in  the  atmosphere.  It  is  often  assumed 
that  one  of  the  first  products  is  formaldehyde.  That  form- 
aldehyde can  polymerize  to  sugars  is  undoubtedly  well 
proved.  The  mechanism  by  which  formalderryde  can  be 
produced  in  the  plant  is  more  difficult  to  discover.  Oxygen 
appears  to  be  evolved  practically  simultaneously  with  the 
absorption  of  carbon  dioxide,  and  therefore  very  elaborate 
chemical  changes  seem  improbable.  The  energy  that  will 


102 


r  PRODUCTS 


be  freed  by  the  combustion  of  dry  plant  materials  equals 
the  amount  of  solar  energy  necessary  for  their  production, 
and  the  animal  energy  obtained  by  consuming  plant 
products  will  also  be  the  same  amount  less  some  forms  of 
waste  (discussed  in  Part  IV.) .  Although  the  actual  mechanism 
by  means  of  which  carbon  dioxide  is  converted  into  complex 
organic  bodies  is  only  very  little  known,  the  substances 
themselves  have  been  the  subject  of  much  elaborate  inquiry. 
The  following  table  gives,  in  brief  form,  the  chief  classes 
of  substances  which  are  produced  in  plants  by  these  means. 


Water— 


Organic 
matter 


TABLE  19. 

Volatile,  such  as  acetic  acid. 
Non-volatile.  Lactic,  citric,  tar- 
taric,  oxalic  acids. 

Pentosans  (guins)  as  araban 

and  xylan. 
Pentoses  (sugars)  as  arabi- 

nose  and  xylose. 
Furfuroids,  lignin,  etc. 
Hexosans  (amylans)  as  cel- 
lulose and  starch. 
Hexoses    (glucoses)   as 

dextrose,  levulose. 
Poly  -  saccharoses      as 

cane  sugar,  etc. 
True  fats  and  oils. 


Resins  and  essential  oils. 
Proteins. 

bodies        |  Amides  and  Amines. 


/Vegetable 
acids 

VO1 

Nor 

tc 

Carbo-           \ 

hydrates 

ce< 

\ 

n-«  

J.IU 

Wa 

TJpe 

xve^ 
i  Pro 

"NTl-f-rV-KYGMl-MlO     I 

\  Mineral  matter 


Phosphates  of  lime,  potash,  and 

other  bases. 
Sulphates  of  lime,  potash,  and 

other  bases. 
Silicates  of  lime,  potash,  and 

other  bases. 
^  Chlorides  of  sodium,  etc. 


Feeding  value. 

(Practically 
none. 

Doubtful. 

Do. 

None. 


Heat-pro- 
ducers. 


Heat  pro- 
ducers. 

No  value. 
Do. 

Flesh- 
formers. 

Small    heat- 
ing values. 

Bone  -  form- 
ing. 

None. 

None. 
Digestive. 


In  some  cases  they  are  very  well-known  organic  substances, 
in  others  they  are  substances  only  described  in  the  advanced 
text-books. 

THE  VEGETABLE  ACIDS. 

Formic  Acid,  H.COOH,  occurs  in  small  quantities  in 
stings  of  nettles,  in  butter  exposed  to  sunlight,  in  the  contents 
of  the  stomach,  and  in  many  fermented  materials.  Formic 


PHOTO-SYNTHESIS  103 

acid  is  a  strong  volatile  acid,  of  pungent  smell,  and  very 
irritating  in  contact  with  scratches  on  the  skin. 

Acetic  Acid,  CH3.COOH,  occurs  in  many  plants, 
is  a  common  product  of  fermentation,  and  is  produced  in 
the  distillation  of  wood  (see  p,  129),  from  which  latter 
source  most  of  the  acid  of  commerce  is  obtained.  It  can 
be  produced  from  coniferous  sawdust,  saturated  with  sodium 
hydroxide,  and  subjected  to  steam  and  air  at  120°  Cent. 
It  is  a  mono-basic  acid,  volatile,  has  a  fairly  strong  smell, 
and  forms  well-recognized  salts,  mostly  soluble  in  water. 
The  purer  acid  is  used  for  pickles  and  other  food  purposes. 
Calcium  acetate  is  used  for  the  manufacture  of  acetone,  and 
for  mordanting  cotton  goods. 

Lactic  Acid,  or  hydroxy  propionic  acid,  CH3.CH(OH).- 
COOH,  is  a  common  product  of  fermentation,  and  is  also 
found  in  muscular  tissue.  It  can  be  manufactured  from 
glucose,  chalk,  and  sour  milk.  It  is  not  volatile,  but  on 
concentration  the  solution  forms  a  lactone  by  loss  of  water. 
This  ability  to  split  off  water  makes  it  a  valuable  hydrolytic 
agent.  In  free  and  uncontrolled  fermentation  the  develop- 
ment of  lactic  acid  proceeds  best  in  the  presence  of  much 
nitrogenous  material.  The  salts  of  lactic  acid  crystallize 
poorly. 

Oxalic  Acid,  (COOH)2.2H2O.— The  oxidation  of  almost 
any  organic  substance  will  produce  some  oxalic  acid.  It 
is  almost  universally  found  in  plants,  but  beet  leaves, 
rhubarb  leaves,  and  sorrel  contain  especially  large  quantities. 
Oxalic  acid  is  manufactured  from  coniferous  sawdust, 
saturated  with  sodium  hydroxide,  subjected  to  steam,  and 
a  large  proportion  of  air,  at  300°  Cent.  The  sodium 
oxalate  so  formed  is  treated  with  sulphuric  acid.  It  is  a 
di-basic  acid,  non- volatile,  forms  good  crystalline  salts 
with  the  alkalies,  whilst  its  calcium  salt  is  marked  by  its 
special  insolubility,  a  property  which  enables  plants  to 
deposit  insoluble  calcium  oxalate  in  their  tissues  as  a  means 
of  getting  rid  of  excessive  quantities  of  this  acid.  Calcium 
oxalate  is  insoluble  in  any  of  the  acids  commonly  found  in 
plants.  Oxalic  acid  is  poisonous  to  both  plants  and  animals. 


104  PLANT  PRODUCTS 

It  is  very  easily  oxidized  in  the  laboratory,  and  becomes 
oxidized  in  the  soil  by  bacterial  action.  In  the  presence  of 
an  excess  of  alkaline  oxalates  the  heavy  metals,  like  iron 
and  copper,  produce  double  salts  with  the  alkalies,  which 
are  soluble. 

The  homologues  of  oxalic  acid  are  also  important.  A 
member  of  the  series,  malonic  acid,  HOOC.CH2COOH,  has 
no  great  interest  for  present  purposes,  but  succinic  acid  is 
present  in  many  plants,  and  is  produced  during  fermentation, 
whilst  its  oxidized  products  are  met  with  in  still  larger 
amounts. 

Malic  Acid,  or  Hydroxy  Succinic  Acid,  HOOC.CH2.- 
CH(OH).COOH,  occurs  in  apples,  gooseberries,  cider,  and 
many  other  fruit  materials. 

Tartaric  Acid,  Dihydroxy  Succinic  Acid,  HOOC.- 
CH(OH).CH(OH).COOH,  is  found  in  considerable  quantities 
in  grapes  and  wine.  The  deposits  in  wine  casks,  known  as 
argol,  is  one  of  the  chief  sources  of  tartaric  acid.  Argol, 
purified  by  crystallization,  is  known  as  tartar,  or  cream  of 
tartar.  The  purified  argol  is  treated  with  calcium  carbonate 
and  calcium  sulphate  to  obtain  a  precipitate  of  calcium 
tartrate,  which  is  subsequently  decomposed  by  sulphuric 
acid.  The  recovered  calcium  sulphate  supplies  all  that  is 
necessary  for  the  former  part  of  the  process.  Tartaric 
acid  is  non-volatile  ;  crystallizes  well ;  is  easily  decomposed 
by  heat,  giving  off  a  smell  of  burnt  sugar  ;  forms  soluble 
salts  with  the  alkalies  ;  insoluble  salts  with  the  alkaline 
earths  ;  complex  ions  with  iron  and  copper  ;  and  produces 
a  potassium  hydrogen  tartrate  which  is  insoluble  in  water, 
though  soluble  with  decomposition  in  either  acids  or  alkalies. 
Tartaric  acid  is  used  medicinally,  for  summer  drinks,  for 
photography,  for  silvering  mirrors,  for  bleaching,  and  for 
dyeing. 

Citric  Acid,  HOOC.CH2.C(OH)(COOH).CH2.COOH+ 
H2O,  is  a  very  common  plant  acid.  L,emons  can  produce 
as  much  as  five  or  six  per  cent.,  and  Dyer  found  that  most 
plant  roots  contained  acids,  largely  citric  acid,  up  to  about 
i  per  cent.  I,emon  juice  is  boiled  with  calcium  carbonate 


PHOTO'S  Y  NTH  ESI  S  105 

till  nearly,  but  not  quite,  neutral,  and  the  calcium  citrate 
formed  acidified  with  sulphuric  acid.  Citric  acid  forms  an 
insoluble  calcium  salt,  which  does  not  easily  form  without 
boiling.  The  deposition  of  calcium  citrate  by  boiling  milk 
in  a  saucepan  is  a  well-known  phenomenon,  which  produces 
a  crust  on  the  bottom  of  the  saucepan,  rather  difficult  to 
remove. 

THE  CARBOHYDRATES. 

Fibre.  —  The  members  of  the  carbohydrate  group, 
which  are  pentosans,  C5H8O4,  that  is  five  carbon  gums, 
are  very  common  in  all  the  fibrous  parts  of  plants. 
Straw  may  contain  up  to  20  per  cent,  of  this  material, 
which  is  consequently  often  known  under  the  name  of 
straw  gum.  The  amount  of  pentosan  present  in  most 
plant  products  is  roughly  in  proportion  to  the  amount  of 
fibre.  No  satisfactory  use  has  been  made  of  straw  gum  as 
yet,  since  its  adhesive  properties  are  too  feeble.  If  the  amount 
of  wheat  grown  in  Great  Britain  is  to  be  doubled,  the  straw 
will  also  be  doubled.  It  is  hence  important  to  discover  new 
uses  for  straw,  and  this  subject  seems  worthy  of  further 
inquiry.  When  heated  with  dilute  acids  the  pentosans  are 
first  converted  into  pentoses,  and  then  condense  into 
furfuraldehyde,  a  volatile  liquid  which  can  be  distilled  with 
steam  and  forms  many  coloured  compounds,  some  of  which 
are  dyestuffs.  Straw  is  the  best  raw  material  for  the 
production  of  furfuraldehyde.  The  pentoses  themselves 
are  not  common  materials  in  plant  life.  The  pectins,  gums, 
and  such  substances,  frequently  yield  substances  of  both 
the  C5  and  C6  groups,  and  are,  therefore,  compound  bodies 
containing  these  two  groups  (see  p.  131).  The  cellulose 
group  is  a  very  common  material  to  find  in  plants,  most  of 
the  stiffening  parts  of  plants  being  due  to  this  substance, 
which,  in  its  pure  form,  approaches  C6H10O6  in  composition. 
Cotton-wool  and  filter  paper  (see  p.  128)  may  be  taken 
as  practically  pure  specimens  of  cellulose.  Cellulose  is 
insoluble  in  all  common  reagents,  but  is  soluble  in  solutions 
of  copper  hydroxide  in  ammonia,  as  well  as  in  zinc  chloride 


io6  PLANT  PRODUCTS 

or  sulphuric  acid.  Solutions  of  cellulose  in  cuprammonium 
hydroxide  are  used  in  making  Willesden  paper  and  canvas  ; 
solutions  in  zinc  chloride  are  used  for  electric  carbon  fila- 
ments ;  and  solutions  in  sulphuric  acid  are  used  for  parch- 
ment paper.  Many  of  the  fibrous  parts  of  plants  are  not 
pure,  but  contain  furfuroids,  lignin,  etc. 

Starch,  (C6H10O6),  or  probably  slightly  more  hydrated, 
is  a  very  common  form  of  storing  reserves  of  plant  foods  in 
seeds,  stems,  bulbs,  and  other  parts  of  a  plant  where  they 
are  not  required  at  the  time,  but  at  some  later  stage  of  the 
plant  growth.  Starch  is  commonly  recognized  by  its 
microscopic  form  and  reaction  with  iodine.  A  microscope 
with  Nicol  prisms  is  of  great  use  in  observing  starch  grains. 
Dry  heat  above  150°  Cent,  converts  starch  into  dextrin. 
In  the  presence  of  water,  starch  grains  burst  when  heated. 
Starch  is  soluble  in  hot  water,  forming  a  colloidal  solution. 
Potato  starch  gelatinizes  at  65°,  but  oat  starch  needs  95° 
Cent.  On  the  addition  of  a  drop  of  copper  sulphate  to  a 
solution  of  starch,  followed  by  a  large  excess  of  sodium 
hydroxide,  a  blue  precipitate  is  produced,  which  is  not 
altered  on  boiling.  The  action  of  ferments,  such  as  diastase, 
turns  starch  into  soluble  products,  dextrin,  malto-dextrin, 
maltose,  etc.  Further  treatment  with  dilute  acid  will 
convert  these  products  into  glucose  (dextrose).  Diastase 
is  a  typical  enzyme,  and  has  the  power  of  converting  1000 
times  its  own  weight  of  starch  into  soluble  materials. 

Dextrin,  a  body  very  similar  to  starch,  is  generally 
present  in  plants  to  a  small  extent,  and  can  be  obtained  by 
heating  starch  either  by  itself  or  in  presence  of  water  or 
with  traces  of  nitric  acid.  It  differs  from  starch  in  giving 
a  red  colour  with  iodine.  Dextrin  is  used  in  place  of  gum, 
especially  in  hot  climates,  as  it  is  less  hygroscopic  than  gum 
arabic.  For  small  articles,  like  postage  stamps,  dextrin 
is  superior  to  gum  arabic,  but  for  large  articles  its  adhesive 
power  is  too  small. 

The  Mono-Saccharoses,  or  Hexoses,  C6H12O6. — 
Glucose  (dextrose,  grape  sugar)  occurs  in  all  the  sweet-tasting 
plants,  crystallizes  with  some  difficulty .  often  with  one  molecule 


PHOTO-SYNTHESIS  107 

of  water  of  crystallization.  It  is  soluble  in  water,  or  alcohol, 
ferments  readily,  rotates  the  plane  of  polarized  light  to  the 
right,  and  reduces  Fehling's  solution,  or  alkaline  solutions 
containing  copper  and  tartaric  acid.  Its  properties  are 
those  of  an  aldo-hexose.  Glucose  is  manufactured  by  boiling 
starch  with  dilute  sulphuric  acid,  removing  the  acid  with 
lime,  and  concentrating  the  liquor. 

Fructose  (laevulose,  fruit  sugar)  is  also  found  in  plants, 
and  differs  from  dextrose,  since  it  is  a  keto-hexose.  Honey 
consists  of  a  mixture  of  glucose  and  fructose.  In  cold  weather 
the  glucose  separates  out  as  crystals,  leaving  the  fructose 
as  a  liquid.  Crystallization  of  fructose  presents  many 
difficulties,  but  the  material  can  now  be  produced  com- 
mercially in  the  solid  form.  Fructose  reduces  Fehling's 
solution,  and  rotates  the  plane  of  polarized  light  to  the 
left. 

Galactose,  a  sugar  closely  resembling  dextrose,  is  not 
generally  found  in  plants,  although  it  is  a  common  result 
of  the  hydrolysis  of  many  of  the  gums,  where  it  occurs 
in  combination  with  one  of  the  pentoses.  It  is  also  a 
constituent  of  raffinose.  Many  forms  of  yeast  do  not  ferment 
galactose. 

The  Di-Saccharoses,  C^H^On.—  Maltose,  the  con- 
densed product  of  two  molecules  of  glucose,  is  contained 
in  malt,  and  is  produced  from  starch  during  the  germination 
of  barley  grains.  It  is  a  product  of  the  hydrolysis  of  starch, 
intermediate  between  dextrin  and  glucose.  Maltose  reduces 
Fehling's  solutions  both  before  and  after  hydrolysis,  but  is 
only  fermented  after  hydrolysis. 

Lactose  (milk  sugar)  is  the  product  of  condensation 
of  galactose  and  glucose.  It  occurs  in  cows'  milk  to  the 
extent  of  between  four  or  five  per  cent.,  and  in  human  milk 
up  to  eight  per  cent.,  but  has  not  been  found  in  plants. 
It  is  made  from  whey,  a  cheese  by-product,  by  crystalli- 
zation, and  is  used  largely  in  medicine. 

Cane  Sugar  (sucrose)  is  the  best  known  of  the  sugars, 
and  is  contained  in  sugar  cane,  sugar  beet,  and  many  other 
sources.  Of  the  sugars  we  have  dealt  with  above,  this  is  the 


io8  PLANT  PRODUCTS 

only  one  which  does  not  reduce  Fehling's  solution  (see 
p.  107). 

The  Tri-Saccharose  (raffinose)  is  the  condensed  product 
of  the  three  mono-saccharoses  glucose,  fructose,  and  galactose, 
and  occurs  in  sugar  beet.  Its  admixture  with  sucrose  is 
neither  easy,  to  detect  nor  resolve.  It  does  not  reduce 
Fehling's  solution,  and  has  the  high  rotary  power  [a]D=+i04°. 

The  Tetra-Saccharose  (stachyose)  is  the  chief  carbo- 
hydrate in  the  Japanese  artichoke.  It  hydrolizes  to  glucose, 
fructose,  and  two  molecules  of  galactose.  It  does  not  reduce 
Fehling's  solution. 

THE  FATS  AND  Oii,s. 

These  are  all  compounds  which  have  glycerine  as  a 
base,  and  one  or  more  of  the  fatty  acids  for  the  acid 
part  of  the  ester.  Oils  are  obtained  from  seeds  either  by 
pressure  or  by  "  Rendering."  The  latter  process  consists 
in  boiling  the  seeds  with  water,  when  the  husks  and  fibre 
sink  and  the  oil  rises  to  the  surface.  With  modern 
methods,  extraction  by  solvents  like  petrol  is  employed. 
The  acids  universally  found  are  stearic  (C18H36O2),  oleic 
(Ci8H34O2),  and  palmitic  (Ci6H32O2).  Other  special  acids 
in  smaller  amount  are  specific  to  particular  plant  products. 
All  the  fats,  on  treatment  with  alkali,  are  hydrolized  with  the 
production  of  soap  and  glycerine.  Glycerine  is  miscible  with 
water,  and  is  non-volatile,  although  it  can  be  distilled  in  a 
vacuum.  The  fatty  acids,  when  unsaturated,  absorb  iodine 
from  solution,  and  the  iodine  absorption  is  closely  connected 
with  the  drying  properties  of  the  oil.  Sulphur  chloride  acts 
on  fats  rapidly.  Both  sulphur  and  chlorine  are  taken  into 
the  molecule.  These  compounds  are  used  as  rubber  substi- 
tutes (see  p.  165).  Free  sulphur  also  acts  upon  the  unsatu- 
rated oils  at  temperatures  above  120°  Cent. 

Some  other  materials,  which  are  extracted  by  ether  in 
the  ordinary  analysis,  do  not  belong  to  the  true  fats  and  oils. 
These  are  waxes,  which  are  often  compounds  of  the  higher 
alcohols,  and  higher  acids.  Whilst  the  fats  and  oils  have  a 
very  high  feeding  value,  the  waxes  have  no  value  as  food. 


PHOTO-S  YNTHESIS  109 

Essential  oils  are  the  volatile  constituents  found  in  plants. 
Turpentine  oil  is  one  of  the  most  important. 


THE  NITROGENOUS  BODIES. 

The  nitrates  are  absorbed  by  plants,  and  are  subse- 
quently converted  into  organic  nitrogen  compounds.  In 
cases  of  drought,  plants  can  store  nitrates  in  their  stems. 
All  the  ordinary  nitrates  are  soluble  in  water.  Ammonia 
salts  are  only  found  in  traces  in  plants.  Plants,  indeed, 
cannot  endure  any  considerable  quantities  of  ammonia,  free 
or  combined  (see  p.  14). 

Ammonia  salts  in  organic  materials  can  be  distilled  out 
with  precipitated  chalk. 

Amides,  Amines,  etc. — Miscellaneous  non-albuminoid 
nitrogenous  bodies  in  plants  are  often  called  amides.  A  por- 
tion of  these  are  true  amides,  but  some  are  not.  Asparagine, 
for  example,  is  both  an  amide  and  an  amino  acid,  which  on 
distillation  with  moderately  strong  alkali  will  yield  half 
its  nitrogen  as  ammonia.  Alkaloids,  nitrogenous  glucosides 
and  amines,  are  also  present. 

The  Albuminoids,  or  the  Proteins,  are  the  complex 
bodies  of  which  the  amino  acids  are  the  basis.  They  can  be 
precipitated  by  copper  hydrate,  lead  acetate,  uranium  acetate, 
or  other  precipitants,  the  non-albuminoid  nitrogenous  matter 
remaining  in  solution.  For  a  rough  division  the  nitrogen 
insoluble  in  lead  acetate  solution  may  be  considered  protein 
nitrogen.  The  ammonia  distilled  by  potash,  but  not  distilled 
by  calcium  carbonate,  can  be  considered  as  amide  nitrogen. 
The  nitrogen  distilled  by  calcium  carbonate  can  be  considered 
as  ammonia  compounds,  and  the  nitrates  precipitated  by 
nitron  can  be  taken  as  the  nitrate  nitrogen.  It  will  not 
infrequently  be  found  in  roots  and  leaves  that  the  sum  of 
these  fractions  of  nitrogen  will  not  add  up  to  the  total 
nitrogen,  but  in  the  case  of  grains,  seeds,  hay  and  straw,  the 
above  division  will  not  give  any  appreciable  surplus  or 
deficiency.  Roughly  speaking,  one  may  say  that  mature 
plants  do  not  contain  any  large  quantities  of  nitrogen  outside 


no  PLANT  PRODUCTS 

the  groups  alluded  to,  but  immature  plants  will  often  have 
some  nitrogen  in  unknown  combinations. 

For  the  production  of  proteins  in  the  plants  it  is  necessary 
to  supply  nitrogen,  phosphorus,  and  sulphur.  The  other 
plant  products  which  do  not  contain  those  elements,  are 
indirectly  dependent  upon  the  proteins,  and  the  production 
of  full  quantities  of  starch  or  sugar  cannot  be  obtained  without 
adequate  supplies  of  fertilizing  ingredients  containing  those 
elements. 

The  waste  of  solar  energy  alluded  to  in  Table  18  shows 
that  much  of  the  energy  of  the  sun  is  expended  in  evaporating 
water.  Experiments,  both  on  the  small  and  on  the  large 
scale,  show  that  the  proper  utilization-  of  fertilizers  results 
in  economy  in  use  of  water  (see  p.  101).  Phosphates 
and  nitrates  appear  to  be  particularly  valuable  in  this  respect. 
The  use  of  top  dressings  of  nitrate  of  soda  or  sulphate  of 
ammonia  during  the  droughty  periods  on  corn  and  hay 
crops  is  a  very  well-known  practice,  whilst  the  use  of 
phosphatic  manures,  either  directly  or  indirectly,  during 
the  stimulus  of  root  development  also  produces  an  economy 
of  water.  The  question  of  the  water  supply  to  the  plant  is, 
therefore,  very  closely  bound  up  with  the  supply  of  proper 
fertilizing  ingredients,  and  much  can  be  done  in  dry  regions 
or  during  dry  periods  to  economize  the  water  supply  by  a 
liberal  use  of  phosphatic  and  nitrogenous  fertilizers. 

REFERENCES   TO   SECTION    I 

Haas  and  Hill,  "  Chemistry  of  Plant  Products,"  p.  143.     (Longmans.) 

Fenton,  Journ.  Chem.  Soc.,  1907,  T.  p.  687. 

Borday,  Proc.  Roy.  Soc.,  1874,  p.  171. 

Warner,  Proc.  Roy.  Soc.,  1914,  B.  87,  p.  378. 

Dyer,  Journ.  Chem.  Soc.,  1894,  T.  115. 

Cross  and  Beavan,  "  Cellulose."     (Longmans  &  Co.) 

Forster,  "  Bacterial  and  Enzyme  Chemistry."     (Arnold.) 

Armstrong,  "  The  Simple  Carbohydrates ;  Monograph  on  Bio-chemistry." 
(Longmans.) 

Rideal,  "  Practical  Organic  Chemistry."     (Lewis.) 

Barnes,  "The  After  Ripening  of  Cane,"  Agric.  Journ.  Ind.,  1917, 
p.  200. 

Bayliss,  "The  Nature  of  Enzyme  Action."     (Longmans.) 

Jorgensen  and  Stiles,  "Carbon  Assimilation."     (Wesley.) 


SECTION  II.— THE  CARBOHYDRATES 
PRODUCED  IN  CROPS 

(a)  Sugar. — Of  the  various  sugars  given  in  Section  I.,  the 
di-sacchacrose  named  sucrose,  or  cane  sugar,  is  by  far 
the  most  important.  Cane  sugar  is  present  in  many  plants, 
and  is  extracted  from  many  different  sources.  Of  these, 
the  sugar  cane  is  the  best  known,  and  oldest  worked.  Sugar 
cane  is  grown  chiefly  in  warm  climates,  such  as  the  Southern 
United  States,  the  West  Indies,  Queensland,  the  Philippines, 
and  India.  The  sugar  cane  grows  best  in  a  good,  deep  soil, 
generally  of  a  dark  colour.  It  is  propagated  from  sets 
in  a  manner  somewhat  resembling  potato  planting  ;  that  is, 
sets  containing  two  or  three  buds  are  planted  a  few  inches 
below  the  surface,  in  a  well-manured  soil.  In  some  places 
entire  canes  are  planted,  but  this  tends  to  produce  an 
irregular  crop.  Irrigation  equal  to  50  inches  of  rain  is  always 
necessary,  unless  the  rainfall  is  exceptionally  heavy.  The 
crop  lasts  about  twelve  months,  and  there  is  some  difficulty 
in  determining  when  it  is  ripe.  Where  irrigated  water  is 
difficult  to  obtain,  mulches  are  not  infrequently  used  on  the 
surface.  In  Mauritius  the  cane  is  often  planted  in  pits. 
Very  frequently  the  crop  is  grown  for  two  or  three  years  in 
succession,  since  after  the  first  crop  has  been  cut  the  old 
stem  tillers  freely,  and  produces  what  is  called  a  ratoon  crop, 
which  i?,  however,  never  equal  to  the  first  year's  growth. 
As  in  all  tall  crops,  "  lodging  "  is  a  serious  cause  of  loss. 
The  side  leaves  have  to  be  removed  during  the  process  of 
cultivation.  Some  system  of  rotation  is  nearly  always 
necessary,  so  that  the  cane  is  not  cultivated  on  the  same 
land  more  than  once  in  five  or  six  years.  The  cane  is  subject 
to  all  kinds  of  pests.  An  interesting  method  for  protection 


112 


PLANT  PRODUCTS 


against  pests  adopted  in  India  is  to  put  castor  cake  and  salt 
into  the  water,  when  the  poisonous  compounds  of  the  castor 
dissolve  in  the  salt  water,  and  destroy  many  pests.  When 
the  crop  is  ripe,  which  takes  about  twelve  months  from 

TABLE  20. — INDIAN  SUGAR. 
Composition  of  Sugar  Canes. 


Thin  cane. 

Thick  cane. 

per  cent. 
I« 

per  cent. 
81 

Juice,  not  expressed  by  Bullock  Mill 
>»       >»           »          »>          j»          >» 
Juice  expressed  (Water) 
(Sugar)    .. 

(Water)  .. 
(Sugar)   .. 

35 
5 
39 
6 

I6i 

61 
ii 

TABLE  21. — SUGAR  CANE,  INDIAN,  200-300  ACRE  PRODUCTION. 
Cost  of  Cultivation  in  Rupees  per  Statute  Acre. 


First  year. 

Second  year. 

Third  year. 

Seed  (sets)    .  . 
Irrigating     .  .           .  , 
Manuring     .  . 
Other  labour 
Boiling,  Marketing  etc. 

Cane. 
50 
60 
I8o 

55 
140 

ist  ratoon. 

50 
100 

45 
125 

and  ratoon. 
40 

40 
90 

Value  of  Brown  Sugar 

485 
56o 

320 
450 

I70 
200 

Profit           

75 

130 

30 

planting,  the  cane  is  usually  cut  with  some  kind  of  sickle,  and 
removed  to  the  mills.  When  cane  is  cultivated  in  primitive 
fashion,  as  is  the  case  in  India,  the  mills  containing  three 
rollers  are  semi-portable  and  are  worked  by  four  bullocks. 
Two  of  the  rollers  are  about  half  an  inch  apart,  and  the 
third  roller  is  only  one-eighth  of  an  inch  from  the  centre 
roller.  By  passing  the  cane  through  the  wide  gap  first,  and 
then  through  the  narrow  gap,  a  double  squeeze  is  given, 
and  about  80  per  cent,  of  the  juice  extracted.  In  the  West 
Indies,  the  United  States  of  America,  and  Queensland,  with 
more  efficient  machinery,  and  by  moistening  the  pressed 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS  113 

cane  with  a  little  water,  as  much  as  90  per  cent,  of  the  j uice 
can   be  extracted.     Excepting    under   the   most   primitive 
conditions,  lime  is  always  used  for  removing  many  of  the 
impurities  in  the  j  uice.     In  the  field  methods  of  manufacture, 
adopted  in  India,  the  lime  is  added  until  the  natural  colour 
of  the  sugar  cane  juice,  which  acts  as  an  indicator,  shows 
that  neutrality  has  been  reached.     The  liquid  is  then  boiled 
down,    and   very   carefully   skimmed.     In   more   elaborate 
and  carefully  industrialized  systems  a  slight  excess  of  lime 
is  used,  then  filtered,  the  excessive  lime  removed,  by  carbonic 
acid,  and  again  filtered.     Some  of  the  proteins  are  precipi- 
tated on  boiling  in  any  case.     In  primitive  systems  the  whole 
material  purified  by  skimming  is  boiled  down  until  it  becomes 
very  thick,  when  it  is  poured  into  moulds.     The  moulds 
often  consist  of  holes  in  the  ground,  lined  with  cloth,  so 
that  some  portion  of  the  molasses  drains  away.     In  such 
a  case  a  brown  sugar  is  obtained.     Where  it  is  desirable  to 
get  a  very  white  sugar  the  boiling-down  process  takes  place 
in  a  vacuum  pan.     Sugar  is  converted  into  caramel,  a  brown 
colouring  matter,  by  the  action  of  heat,  but  by  reducing 
the  pressure,  and  therefore  the  boiling  point,  the  heat  is 
lowered  to  less  than  the  temperature  at  which  sugar  begins 
to  caiamelize.     Further  improvement  can  be  adopted  by 
separating   the  molasses  from  the  sugar  by  a  centrifugal 
machine.     A  small  centrifugal  machine,  worked  by  hand, 
can  be  obtained  for  field  use.     In  India,  brown  sugar  is 
preferred  to  white  sugar,  and  hence  little  effort  is  made  to 
carry  the  purification  to  any  extent.     The  supply  of  fuel 
is  always  an  important  point  in  the  manufacture.    The  waste 
cane,  if  dried,  makes  a  useful  fuel,  and  the  dried  side  leaves, 
unless  required  for  fodder,  can  also  be  used  as  fuel.     In 
India  the  upper  leaves  are  used  to  feed  the  bullocks.     For 
the    satisfactory    cultivation    of    sugar    cane    nitrogenous 
fertilizers  are  essential,  and  in  experimental  work  conducted 
in  India  quantities  of  from  two  to  five  hundred  pounds  per 
acre  of  nitrogen  have  been  used,  although  the  larger  quantity 
seems  unnecessary.    Other  manures,  such  as  phosphatic  and 
potassic  ones,  are  sometimes  necessary,  but  not  to  anything 
D.  8 


H4  .  PLANT  PRODUCTS 

like  the  extent  that  nitrogenous  ones  are.  It  appears  to 
be  necessary  that  the  nitrogen  should  always  be  in  much 
larger  proportion  than  the  other  fertilizing  ingredients. 
Indeed,  where  this  has  not  been  the  case,  individual  observers 
have  not  infrequently  reported  that  phosphates  have  done 
harm,  but  that  is  only  a  particular  case  of  the  importance 
of  preserving  a  proper  balance  of  fertilizers,  which  has  so 
often  been  alluded  to.  In  experimental  results  obtained 
under  good  conditions  in  India  quantities  amounting  to 
nearly  five  tons  of  crude  sugar  per  acre  have  been  obtained. 
At  the  larger  industrialized  concerns  in  the  United  States 
about  10  or  12  per  cent,  of  the  weight  of  cane  is  obtained 
as  sugar.  In  vegetarian  countries  sugar  replaces  the  meat 
of  meat-consuming  countries,  and  the  amount  produced  on 
the  small  scale  is  in  excess  of  anything  recorded  in  ordinary 
Government  statistics.  Considerable  quantities  of  softer 
canes  are  never  made  into  sugar  at  all,  but  are  eaten  as 
they  are. 

Sugar  Beet. — In  temperate  climates  the  sugar  cane 
does  not  ripen  satisfactorily,  and  sugar  is  therefore  prepared 
mostly  from  the  sugar  beet.  Sugar  beet  is  a  crop  which 
closely  resembles  the  mangel  wurzel  in  its  properties.  An 
enormous  amount  has  been  written  upon  this  subject,  and 
there  is  no  particular  reason  why  the  sugar  beet  should  not 
be  cultivated  in  many  parts  of  the  British  Isles.  Sugar  beet 
can  certainly  be  grown  in  the  north  of  England,  as  well  as 
in  the  south,  but  if  grown  will  replace  some  of  the  other 
crops.  Whether  that  will  be  a  profitable  arrangement  only 
the  future  can  tell.  The  manufacture  of  sugar  from  sugar 
beet  follows  a  somewhat  different  course  to  that  of  the  sugar 
cane.  The  system  adopted  is  called  the  diffusion  process. 
In  the  process  the  sugar  beet  is  cut  into  slices,  extracted  with 
water  (at  85°-90°  Cent.),  and  the  weak  solution  obtained  used 
to  make  a  stronger  solution  by  extracting  more  beet.  The 
concentration  of  the  sugar  liquors  rises  until  it  becomes 
approximate  to  the  strength  of  the  juice  in  the  beet  them- 
selves, that  is  to  say,  it  rises  to  nearly  18  per  cent,  of  sugar. 
This  process  has  the  great  advantage  that  the  cell-wall  of 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS  115 

the  beet  itself  is  used  as  the  filter  and  purifier.  The 
albuminoids  and  the  gums  do  not  diffuse  through  the  cell- 
wall  as  readily  as  the  sugar,  and  therefore  the  sugar  solution 
obtained  is  in  a  much  purer  condition  than  that  obtained 
from  the  sugar  cane.  The  other  substances  present  in  raw 
cane  sugar  are  pleasant  to  the  taste,  and  probably  most 
people  prefer  the  flavour  of  brown  sugar  to  white  when  it  is 
made  from  cane.  It  is  rather  the  appearance  of  white  cane 
sugar  that  gives  it  a  high  value.  The  impurities  in  sugar 
beet  include  substances  which  are  bitter  to  the  tongue 
and  musty  smelling  to  the  nose,  and  the  purification  does 
not  entirely  remove  these  impurities,  though  they  are  too 
small  in  amount  to  estimate.  The  general  process  of 
purification  is  much  the  same  as  in  the  case  of  cane.  Where 
the  resulting  beet  slices  extracted  can  be  used  as  cattle 
food  it  may  easily  be  more  profitable  not  to  attempt  to  remove 
the  last  trace  of  sugar,  but  to  leave  a  little  in  for  the  cattle 
food.  The  cultivation  of  sugar  beet  accommodates  itself 
well  to  the  ordinary  types  of  mixed  agriculture  adopted  in 
temperate  climates,  especially  where  the  production  of  milk 
and  meat  form  an  essential  part  of  agriculture.  This  is 
an  undoubted  advantage  which  the  sugar  beet  possesses  over 
the  sugar  cane,  inasmuch  as  the  sugar  cane  gives  no  useful 
by-product  and  does  not  lend  itself  so  well  to  the  working 
of  the  general  agricultural  plan. 

About  eleven  tons  of  clean  beet  per  acre  represent 
the  European  average  production,  with  about  16  per  cent,  of 
sugar  obtainable  from  them,  or,  say,  roughly  two  tons  of 
sugar  per  acre.  This  is  much  below  the  best  production 
of  cane  sugar,  but  it  is  very  difficult  to  get  average  figures  of 
the  production  of  cane  sugar,  since  there  are  such  large 
amounts  grown  in  a  very  primitive  manner.  Experience 
is,  however,  showing  that  no  nation  can  afford  to  be  entirely 
dependent  upon  outside  sources,  and  at  least  some  fraction 
of  the  necessary  sugar  may  have  to  be  grown  in  Great 
Britain,  even  if  it  is  not  economically  profitable.  The  other 
parts  of  the  British  Empire  are  more  nearly  self-supporting 
as  regards  sugar. 


n6  PLANT  PRODUCTS 

The  Date  Palm  is  also  one  of  the  minor  sources  of 
sugar.  Most  species  of  the  palm  can  be  used  for  the 
production  of  sugar ;  many  of  them  are  used  for  the 
production  of  sugar  for  fermentive  processes.  When  it  is 
desired  to  manufacture  sugar  the  palm  is  cut,  and  the  sugar 
juice  runs  into  a  pot.  The  pots  are  collected,  and  the  juice 
quickly  boiled  down  before  fermentation  takes  place.  With 
the  aid  of  a  hand  centrifugal  machine  very  pure  sugar  can 
be  obtained  in  a  simple  manner.  The  quantity  made  is, 
however,  small,  and  can  never  compete  commercially  with 
the  other  sources  of  sugar. 

Sugar  Refining. — Most  of  the  sugar  industry  in  the 
British  Isles  in  the  past  has  rather  turned  on  the  purifica- 
tion of  crude  sugars  produced  elsewhere.  Many  reasons 
have  been  given  for  the  collapse  of  the  sugar  purification 
industry  in  the  British  Isles.  If  reference  be  made  to  an 
old  work  by  Higgins,  dated  1797  (see  Bibliography),  the 
following  will  be  found :  "  It  is  now  well-known  that  an 
artist  with  a  very  little  education  will  soon  learn  all  that 
is  useful  to  him  in  mechanics  and  chemistry."  If  such 
opinions  were  generally  held,  the  collapse  of  the  industry 
is  readily  understood. 

Turnips,  etc. — A  very  large  amount  of  sugar  is 
produced  and  consumed  in  the  form  of  swedes,  turnips, 
and  mangolds.  These  crops  form  the  essential  part  of  a 
rotation,  and  permit  the  cleaning  of  the  land.  Good  seed 
beds  and  liberal  manuring  are  essential,  and  the  land  is  usually 
worked  into  ridges.  Super-phosphate,  sulphate  of  ammonia, 
and  potash  salts  are  all  used  as  well  as  farmyard  manure. 
For  mangolds,  salt  is  needed  as  well.  The  seed  is  generally 
used  somewhat  generously,  the  young  plants  being  "  singled," 
that  is  to  say,  all  those  that  are  not  needed  are  hoed  out. 
In  the  United  Kingdom,  about  twenty -four  million  tons  of 
turnips  and  swedes  are  grown.  The  swede  crop  in  the 
northern  counties  contains  about  6  per  cent,  of  sugar,  on  the 
average  a  little  more.  The  average  for  the  whole  country 
is  probably  slightly  less,  and  the  white  turnips  will  be 
distinctly  lower,  but  it  is  probably  not  seriously  wrong  if 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS    117 

we  say  that  there  is  about  5  per  cent,  of  sugar  in  those  twenty- 
four  millions  of  tons  ;  that  is  to  say,  there  is  well  over  a 
million  tons  of  sugar  grown  in  the  British  Isles  and  eaten 
chiefly  by  cattle  in  the  form  of  turnips  and  swedes.  In 
addition  to  that,  there  are  about  ten  millions  of  tons  of 
mangolds  grown,  which,  on  the  average,  will  have  a  rather 
higher  percentage  of  sugar.  Taking  all  together,  there 
cannot  be  much  less  than  one  and  a  half  millions  of  tons  of 
sugar  produced  in  the  British  Isles  and  consumed  in  this 
way,  or,  roughly,  one-tenth  of  the  world's  production  of 
cane  and  beet  sugar.  In  the  case  of  the  mangold,  much  of 
the  sugar  is  cane  sugar,  in  the  case  of  turnips  and  swedes  much 
of  it  is  glucose.  The  crops  of  swedes,  turnips,  and  mangolds 
all  present  some  points  of  similarity,  requiring  good  manuring 
and  a  fairly  deep  soil.  All  of  these  sources  of  sugar  could 
be  used  for  fermentive  purposes  for  the  production  of  alcohol 
if  the  necessity  arose.  During  the  war,  an  increased  fraction 
has  been  used  directly  as  human  food.  Some  fraction  might 
be  used  for  the  manufacture  of  jam.  No  doubt  a  mixture 
of  swede  turnip  pulp  and  fruit  boiled  down  would  not  be 
a  first-class  jam,  but  it  would  be  better  than  letting  the  fruit 
waste.  Unfortunately,  turnips  do  not  ripen  till  after  most 
of  the  fruit  is  over,  but  some  of  the  later  fruits  might  be 
used.  Sugar  beet  will  keep  well,  and  could  be  held  over  the 
winter,  when  it  might  be  used  for  the  preservation  of  early 
summer  truits.  Sugar  beet  can  be  dried  easily,  and  ground 
in  the  mill  to  powder,  when  a  crude  sugar  results.  As 
war  measures,  such  schemes  are  worth  a  trial. 

(b)  Starch. — Starch  is  chiefly  produced  in  cereal  crops, 
although  it  is  a  common  ingredient  of  many  forms  of  plant 
life.  Excepting  in  some  of  the  oil  seeds,  it  may  be  found  in 
any  of  the  finished  forms  of  plant  life,  and  is  one  of  the  food 
reserves  of  the  plant.  The  methods  of  preparing  starch  are 
almost  independent  of  its  origin.  The  systems  chiefly 
employed  are — 

(i)  The  fermentation  process,  in  which  the  material, 
after  being  ground  up  with  water,  is  allowed  to  ferment. 
The  fermentation  results  in  the  solution  of  the  albuminous 


n8  PLANT  PRODUCTS 

part,  and  the  liquor  is  then  run  off,  leaving  the  starch  as  a 
deposit.  After  washing  once  or  twice,  the  starch  is  left. 
This  method  is  rather  wasteful,  as  it  is  not  easy  to  get  more 
than  30  per  cent,  of  any  of  the  grains  in  the  form  of 
starch. 

(2)  Alternative  methods  consist  in  macerating  the  raw 
material  with  water,  and  passing  through  a  fine  sieve, 
containing  about  two  hundred  meshes  to  the  linear  inch. 
The  glutinous  parts  remain  on  the  sieve,  while  the  fine 
grains  pass  through  in  the  water.  The  muddy  starch  liquor 
is  then  allowed  to  settle,  and  the  liquor  is  poured  off,  and 
the  starch  dried.  Combinations  of  these  processes  are 
not  infrequently  used,  in  which  a  certain  amount  of 
fermentation  is  permitted,  and  some  kind  of  sieving  method 
is  employed.  In  more  modern  systems  it  is  not  uncommon 
to  employ  sodium  hydrate  and  sulphurous  acid  as  convenient 
means  of  dissolving  the  proteins  and  obtaining  a  purer 
starch.  Starch  must  either  be  dried  without  any  heat, 
or  a  very  low  degree  of  heat  must  be  maintained,  otherwise 
the  starch  becomes  gelatinized.  Potato  starch  gelatinizes 
readily,  but  rice  starch  with  difficulty.  The  large  starch  grains 
gelatinize  most  readily.  Air-dried  starch  will  usually  contain 
about  20  per  cent,  of  water,  and  that  dried  with  a  moderate 
degree  of  heat  contains  only  10  per  cent.  The  starch  consists 
of  very  small  grains,  which  are  recognized  under  the 
microscope  by  their  characteristic  form  and  size.  Potato 
starch  grains  are  large  and  rice  starch  grains  small. 

Wheat. —  Wheat  constitutes  one  of  the  most  important 
of  the  cereals  which  contain  a  high  percentage  of  starch. 
Wheat  is  grown  in  almost  all  parts  of  the  world,  best  on  a 
fairly  heavy  soil,  and  in  a  climate  which  is  neither  very 
damp  nor  very  dry.  Arid  regions  can,  however,  with  the  aid 
of  irrigation,  produce  very  fine  wheat  crops.  The  intro- 
duction of  irrigation  into  the  Punjab,  in  India,  has  resulted 
in  converting  some  almost  useless  land  into  very  excellent 
wheat  country  and  the  growth  of  wheat  in  Egypt  is 
dependent  on  irrigation.  Wheat  is,  of  all  the  crops,  the  one 
which  can  be  cultivated  for  the  longest  period  of  time  on 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS  119 

the  same  land  without  change,  but  the  best  yields  are  obtained 
on  virgin  lands,  or  under  systems  of  mixed  farming  with 
rotation.  The  yields  per  acre  in  the  British  Isles,  and  in 
Canada,  are  generally  about  30  bushels,  but  the  yield  in 
some  other  parts  of  the  world  does  not  amount  to  more 
than  about  one-quarter  of  that  figure  (see  p.  206).  The 
use  of  nitrogenous  manures  for  wheat  is  important.  The 
desirability  of  top  dressing  with  such  a  manure  as  sulphate 
of  ammonia  has  been  alluded  to  in  Part  L,  Section  I. 
As  a  rule,  wheat  is  not  used  for  the  industrial  manufacture 
of  starch,  because  wheat  commands  too  high  a  price. 

Maize.  —  Three-quarters  of  the  world's  supply  of 
maize  is  grown  in  North  America,  but  the  advantages  of 
maize  are  gradually  becoming  more  and  more  recognized 
in  the  warmer  parts  of  the  globe.  It  is  better  suited  to 
higher  temperatures  than  wheat,  and  though  much  benefited 
by  a  sufficient  rainfall,  is  capable  of  developing  in  drier 
situations  than  wheat.  The  actual  amount  of  maize 
yielded  is,  however,  not  dissimilar  to  that  of  wheat,  and 
in  mediumly  warm  districts  the  two  cereals  compete  with 
one  another.  In  cooler  climates  maize  does  not  ripen 
satisfactorily,  though  the  crop  is  often  used  as  green  fodder. 
The  growth  of  maize  is  very  rapid,  four  months  being  not 
infrequently  sufficient.  As  a  rule,  it  is  best  grown  under 
some  system  of  rotation,  needs  fairly  deep  and  thorough 
cultivation,  and  is  improved  by  fair  dressings  of  farm- 
yard manure,  lime,  phosphates,  potash,  and  sulphate  of 
ammonia.  On  the  large  scale  it  is  often  planted  in  heaps 
three  or  four  feet  apart,  so  as  to  allow  of  cultivation  in 
between.  The  plant  grows  from  about  five  to  twelve  feet 
high.  Much  of  the  crop  is  fed  to  stock,  a  large  fraction 
husked  in  the  field  and  sold  for  manufacturing  purposes. 
Maize  is  admirably  suited  for  the  manufacture  of  starch, 
and  in  the  United  States  of  America  forms  the  chief  source 
of  all  forms  of  that  article.  The  composition  of  maize  is 
very  constant  at  about  70  per  cent,  carbohydrates,  mostly 
starch,  and  about  4  to  5  per  cent.  oil.  Maize  germ  meal,  the 
germ  after  extracting  the  oil,  is  used  as  cattle  food.  Gluten 


120  PLANT  PRODUCTS 

feed  meal,  the  residue  from  starch  factories,  is   used   for 
cattle  food,  and  is  rich  in  albuminoids. 

Rice. — Rice  is  a  cereal  particularly  suited  to  wet  situa- 
tions. It  is  grown  chiefly  in  Bengal  and  Burmah,  but  is  also 
sown  in  Japan  and  China.  The  number  of  varieties  of  rice 
seems  almost  unending.  In  India  there  are  several  different 
groups  of  varieties  which  belong  to  the  seasons.  The  winter 
rice  is  generally  sown  in  May  or  June,  the  autumn  rice  is 
usually  sown  in  August,  the  summer  rice  in  January  or 
February.  The  growth  of  the  crop  is  extremely  varied, 
according  to  the  type  of  cultivation,  some  of  the  very  rapid 
varieties  being  able  to  grow  in  about  two  months,  and  some 
of  the  very  slow  ones  taking  the  best  part  of  a  year.  On 
the  average,  however,  two  crops  are  obtained  in  the  year. 
The  best  type  of  soil  is  a  sandy  one,  lying  upon  clay,  where 
the  irrigating  water  can  be  flooded,  held  up  by  the  subsoil, 
and  yet  leave  the  surface  soil  sufficiently  open  for  the 
growth  of  the  plant.  With  very  wet  varieties  the  depth  of 
water  may  be  so  great  on  the  fields  that  the  workers  actually 
use  boats  to  transport  them  over  the  field ;  but  in  the  hill 
regions,  where  the  slopes  are  often  terraced,  only  an  inch  or 
so  of  water  is  used  for  irrigating  purposes.  Rice  is  best 
sown  in  a  seed  bed  and  transplanted.  Not  infrequently 
the  ploughing  operations  are  carried  out  under  water,  so 
that  the  bullocks  have  to  wade  through  to  do  their  work. 
On  those  lands  that  permit  of  such  treatment,  where  the 
growth  of  the  rice  is  excessive,  the  young  rice  is  grazed  by 
cattle,  in  a  similar  way  to  wheat  being  grazed  by  sheep  in 
temperate  climates.  There  are  no  less  than  about  seventy 
millions  of  acres  of  rice  in  India.  The  rice,  as  separated  by 
threshing,  contains  a  large  amount  of  husks,  and  in  this 
form  is  commonly  called  paddy,  the  term  rice  being  retained 
for  the  finished  product  after  husking.  The  term  "  paddy  " 
is  frequently  employed  with  reference  to  the  whole  system  of 
cultivation,  and  the  terms  "paddy  fields  "  and  "paddy  bird  " 
are  more  commonly  in  use  in  the  east  than  the  term  "  rice," 
which  chiefly  refers  to  the  finished  article  ready  for  the  table. 
In  the  countries  where  rice  is  grown,  the  terms  "  paddy  "  and 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS  121 

"  rice  "  are  used  in  the  same  way  as  sheep  and  mutton  are 
used  in  England.  The  rice  kernel  is  enclosed  in  a  very  hard 
husk,  which  requires  considerable  amount  of  work  over  its 
separation.  On  a  small  scale  rice  is  pounded  by  hand  as  the 
recognized  work  of  the  women  of  India.  On  the  large  scale  in 
Burmese  mills  rice  is  decorticated  by  machinery.  The  husks 
so  removed  are  quite  worthless,  but  the  resulting  grain  is 
very  frequently  polished  still  further  to  produce  white  rice. 
The  resulting  white  rice  is  much  less  nutritious  than  the 
streaked  brown  rice,  which  contains  the  bran  adhering  to 
it.  White  polished  rice  kernels  are  very  nearly  pure  starch, 
whilst  rice  bran  contains  most  of  the  oil  and  albuminoids 
of  the  grain.  The  following  table  represents  the  varying 
composition  of  the  different  parts  of  the  rice  plant : — 

TABLE  22. 


Rice. 


Grain. 

Bran. 

Husk. 

Straw. 

Moisture 

I2'8 

I0'3 

8-0 

7-0 

on    

1'3 

I2'0 

3*5 

2'I 

Albuminoids 

4-9 

"'3 

4'3 

i  -8 

Other  nitrogenous  matter 

2-4 

I'O 

0-8 

0-9 

Carbo-hydrates,  Pentosans,  etc. 

trace 

3-2 

IO'I 

18-5 

„            „         Hexosans,  etc. 

76-5 

44  -6 

24'2 

26-8 

Woody  fibre 

11 

8-6 

25'9 

27'3 

Mineral  matter 

I'O 

9-0 

23-2 

15-6 

lOO'O 

lOO'O 

lOO'O 

lOO'O 

Total  nitrogen 

116 

1-90 

0-69 

0-43 

Total  phosphoric  acid 

0-36 

0-60 

0-63 

0'2I 

Total  potash 

0-17 

o'37 

0-51 

0*69 

Total  lime 

0-04 

0-15 

o'35 

0'35 

Insoluble  silicates    .  . 

0-28 

2*00 

2O  'OO 

I2'80 

Rice  may,  when  merely  ground  into  a  powder,  serve  the 
purpose  of  starch,  or  the  starch  may  be  prepared  from  rice 
by  the  usual  methods  (see  p.  117).  Both  maize  and  rice 
lend  themselves  to  the  possibility  of  producing  starch  by 
the  dry  method  of  grinding  and  blowing  by  currents  of  air, 
but  starch  is  chiefly  made  by  one  of  the  wet  methods. 


122  PLANT  PRODUCTS 

Potatoes. — The  potato,  although  well  known  and 
popular  to-day,  is  a  very  recent  introduction  into  general 
use.  It  is  cultivated  entirely  from  the  tuber  Itself,  and 
not  from  the  seed  of  the  plant.  The  true  seed  of  the  plant 
produced  from  the  flowers  does  not  yield  usable  potatoes 
for  two  or  three  years,  after  which  time  new  varieties  of 
potatoes  are  obtained  and  have  often  fetched  extravagant 
prices.  The  old  varieties,  in  process  of  time,  tend  to  die  out. 
From  the  strictly  botanical  point  of  view,  it  must  be  remem- 
bered that  all  the  potatoes  of  one  kind  in  the  world  are  really 
one  single  plant.  They  have  all  come  from  one  single  true 
seed,  and,  like  all  living  things,  the  individual,  in  process  of 
time,  dies,  and  there  appears,  therefore,  to  be  a  limit  to  the 
life  of  any  particular  so-called  variety  of  potato,  since  each 
variety  is  only  an  individual.  The  potato  loves  much 
manure,  especially  farmyard  manure,  but  also  gives  good 
results  from  the  use  of  sulphate  of  ammonia  and  super- 
phosphate and  sulphate  of  potash.  Good  cultivation  is 
also  essential  for  big  crops.  It  is  a  crop  which  is  particularly 
suited  to  small  types  of  cultivation.  It  appears  to  grow  in 
most  types  of  soil,  though  it  likes  a  fairly  open  kind,  but 
plenty  of  spade  work  and  manure  will  go  a  long  way  to 
remedy  any  excessive  heaviness  a  particular  soil  may  possess, 
and  sprouting  the  potatoes  before  planting  will  reduce  risk 
from  early  frosts.  Five  to  eight  tons  per  acre  of  potatoes 
represent  about  ordinary  farm  experience.  Six  to  eleven 
tons  per  acre  are  recorded  as  market  garden  results.  The 
potato  contains  about  75  per  cent,  of  water,  20  per  cent,  of 
carbohydrates,  and  18  per  cent,  of  starch,  but  higher  figures 
for  solids  can  be  obtained,  especially  where  the  manuring 
has  not  been  so  generous.  In  the  uncooked  state  potatoes 
often  prove  slightly  irritating  when  eaten,  but  when  cooked 
this  difficulty  is  removed.  Potatoes  can  be  dried  by 
machinery  for  the  production  of  potato  flour.  They  can 
also,  after  pulping  or  rasping,  be  used  for  the  manufacture 
of  starch.  Potato  starch,  after  fermentation,  is  used  for 
the  production  of  alcohol. 

In  comparing  the  relative  values  of  maize  and  potatoes 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS    123 

for  the  production  of  starch  much  will,  of  course,  depend 
upon  the  particular  circumstances,  but  a  ton  of  maize  per 
acre  will  be  a  fairly  good  crop,  and  will  barely  produce  half 
a  ton  of  starch.  This  might  be  compared  with  about  seven 
tons  of  potatoes  per  acre,  producing  rather  over  a  ton  of 
starch.  The  cultivation  of  potatoes,  to  yield  good  crops,  is, 
however,  expensive,  in  comparison  with  most  of  the  cereals. 
Potatoes,  if  kept  cool,  can  be  stored  quite  satisfactorily. 
The  large  amount  of  water  they  contain  is  an  objection  for 
transport  purposes  in  comparison  with  the  cereals. 

Sago. — The  sago  palm  grows  in  tropical  countries,  best 
on  boggy  soils,  which  are  rich  in  humus.  The  palms  are 
cut  down  when  the  trunks  have  attained  a  height  of  about 
twenty  feet,  the  sap  is  allowed  to  drain,  and  the  trunks, 
sawn  into  lengths,  split  open,  and  the  pith  removed.  The 
pith  consists  of  starch,  mixed  with  fibrous  materials,  which 
is  then  pounded  in  mortars,  agitated  with  water,  and  the 
starch  separated  as  usual.  The  sago  flour  so  obtained  is 
imported  into  this  country,  and  is  used  for  the  manufacture 
of  glucose,  and  in  the  textile  industries.  The  granulated 
sago  which  is  made  for  the  purpose  of  food  is  prepared 
from  sago  flour  by  mixing  it  with  water  into  a  very  stiff 
paste,  and  gelatinizing  by  heat.  "  Granulated  sago  "  is, 
however,  sometimes  made  from  starches  of  other  origin 
than  sago. 

Cassava  and  Tapioca. — The  tuberous  roots  of  the 
shrub-like  plants  called  sweet  cassava  and  bitter  cassava 
are  cultivated  in  the  tropics  for  edible  purposes.  Cassava 
flour  only  contains  2  pei  cent,  albuminoids.  Owing  to  the 
low  demands  of  cassava  for  mineral  matter,  the  crop  is  very 
well  suited  for  poor,  sandy  soils,  but  it  requires  a  good  supply 
of  air  and  water.  The  cultivation  is  as  that  of  potatoes 
and  similar  manuring  gives  increased  crops.  The  yield  is 
about  5  tons  per  acre,  producing  i  ton  of  starch  and  a  little 
cane  sugar.  Tapioca  is  made  from  cassava  starch  by  stirring 
the  damp  starch  on  hot  iron  plates.  Cassava  root  contains 
a  cyanogenetic  glucoside,  which  develops  prussic  acid  in 
the  same  manner  as  linseed  (see  p.  137).  As  in  the  case 


i24  PLANT  PRODUCTS 

of  linseed  the  crops  grown  at  high  temperatures  yield  most 
prussic  acid. 

Barley,  though  a  starchy  cereal,  is  not  used  directly 
for  the  production  of  starch.  The  best  is  used  for  beer,  the 
second  for  bread,  and  the  worst  for  cattle.  It  is  converted 
into  malt  by  steeping  the  grain  at  a  temperature  of  from 
50°  to  55°  Fahr.,  spread  in  well- ventilated  spaces,  and 
stirred  well  to  permit  germination  and  oxidation  to  take 
place.  It  is  then  dried  at  100°  to  107°  Fahr.  The  higher  the 
temperature,  the  lower  is  the  diastase  activity.  It  is  then 
thrown  on  to  screens,  for  the  removal  of  the  malt  coombes 
or  culms,  which  latter  are  used  for  feeding  cattle. 

(c)  Cellulose. — Cellulose  forms  the  important  chemical 
compound  which  constitutes  the  structural  part  of  nearly 
all  vegetable  matter.  There  are  a  great  many  varieties  of 
cellulose,  and  the  term  must  be  taken  as  denoting  a  group, 
and  not  an  individual.  Cellulose  is  much  more  resistant 
to  chemical  reagents  than  the  other  carbohydrates,  and 
is  isolated  from  vegetable  raw  material  by  hydrolysis  with 
acids  and  alkalies,  or  by  the  more  drastic  action  of  chlorine, 
bromine,  or  sulphur  dioxide. 

All  cellulose  materials  condense  a  fair  amount  of  moisture 
on  their  surface.  In  the  green  plant  cellulose  occurs  in  a 
fairly  hydrated  condition,  but  by  long  drying  or  immersion 
in  alcohol  dehydration  takes  place,  so  that  the  amount  of  cel- 
lulose obtained  from  a  material  by  any  method  of  hydrolysis 
depends  upon  the  degree  of  hydration  to  which  the  cellulose 
has  been  subjected.  This  has  an  important  bearing  upon 
the  subject  of  the  feeding  of  materials  containing  much 
cellulose,  since  grass  that  is  grazed  by  cattle  in  a  wet  condition, 
and  has  never  become  dry,  is  more  digestible  than  the  same 
grass  after  it  has  been  dried  in  the  process  of  making  hay. 
It  is  well  known  in  practical  farming  that  hay  which  has  been 
made  in  exceptionally  dry  weather  is  not  equal  in  feeding 
value  to  that  made  in  weather  which  does  not  permit  of 
such  rapid  and  complete  drying.  Cellulose  enters  into  a 
feeble  composition  with  alkalies  when  treated  with  sodium 
hydrate,  and  produces  alkali  cellulose,  hence  many  forms  of 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS   125 

cellulose  persistently  retain  ash,  some  of  which  has  probably 
been  in  forms  of  partial  combination.  All  forms  of  cellulose 
on  destructive  distillation  yield  charcoal  and  a  distillate 
containing  acetic  acid  and  tar.  As  a  rule,  pure  cellulose 
yields  from  30  to  40  per  cent,  of  charcoal,  and  only  i  to 
2  per  cent,  of  acetic  acid.  The  effect  of  distilling  crude 
cellulose,  such  as  timber  waste,  is,  however,  very  different. 

Cotton. — Cotton  grows    chiefly  in   tropical    and    sub- 
tropical   regions,   and  requires  a  fair  degree  of  moisture 
and  a  moderately  heavy  soil.     It  grows  as  a  small  shrub, 
and  is  planted  at  sufficient  distances  to  allow  hoeing  and 
picking  by  hand.     In  India  two  crops  are  sometimes  obtained 
in  a  year,  but,  as  a  rule,  fallow  or  millets  (Juari,  bajra)  or 
pulses  (gram)  alternate.    In  the  United  States  a  three-course 
rotation  is  adopted,  with  a  resulting  increase  in  the  yield 
of  fibre.     The  plant   yields   a  seed,   to  which  the  cotton 
fibres  adhere.     Some  varieties  have  only  long  fibres,  which 
are   easily   detached.     Other   varieties   have,    in   addition, 
small  short  fluff,  which  refuses  to  come  off  by  any  simple 
process.     Cotton  fibre  is  a  hollow,  flattened,  and  twisted 
tube  in  the  better  varieties  (Sea  Island),  from  about  ij  to 
2  J  inches  long  ;  in  the  Egyptian  kind  the  fibres  are  generally 
from  ij  to  2j  inches  long,  and  in  the  Indian  the  fibres  are 
usually  not  more  than  about  one  inch  in  length,  but  in  Indian 
cotton  considerable  amounts  of  short  fluff  remain  adhering 
to  the  seed.     Those  varieties  which  produce  a  naked  seed, 
that  is,  a  seed  from  which  the  long  fibres  are  easily  removed, 
leaving  the  seed  naked,  are  commonly  called  black  seed. 
Indian  varieties,  owing  to  the  adhering  fluff,  are  called  white 
seed.     After  the  cotton  fibre  has  been  removed,  the  cotton 
seed  still  has  a  considerable  value,  and  is  used  as  an  oil 
seed  (see  p.   137).     Cotton  flowers  are  used  for  dyes.     The 
cotton  is  bound  with  iron  bands  into  bales,  either  circular 
or  rectangular.     On  arrival  at  the  mills,  the  bales  are  broken 
up  and  cleaned.     The  cotton  fibre  is  then  carded,  passed 
through  a  drawing  machine,  and  finally  made  into  thread. 
It  is  then  commonly  woven  into  some  kind  of  fabric  for 
the  production  of  cotton  cloth.     Cotton  is  "  mercerized," 


126  PLANT  PRODUCTS 

by  treatment  with  caustic  soda,  when  it  becomes  stronger 
and  more  glossy. 

Linen. — The  flax  plant,  like  cotton,  has  a  double 
utility.  The  flax  plant,  or  linseed,  grows  in  temperate 
climates,  and  can  be  used  either  for  the  production  of  fibre 
for  flax,  or  linseed  for  food  and  oil,  but  not  usually  with 
much  satisfaction  for  both.  The  crop  is  rarely  grown  more 
often  than  once  in  six  or  eight  years,  and  does  not  need  a  soil 
in  a  very  high  condition.  I/inseed  is  sown  on  the  flat  in 
well-ploughed  land.  Potash  fertilizers  are  good,  but  phos- 
phates only  encourage  weeds.  The  plants  are  preferably 
pulled  by  hand,  when  the  plant  is  only  two -thirds  of  its 
full  height,  that  is,  pulled  about  twenty  inches  high.  The 
seeds  are  then  either  beaten  or  ripped  off,  and  the  straw  or 
flax  is  retted,  or  rotted,  by  immersion  in  soft  water.  In 
some  cases  the  flax  stems  are  merely  spread  out  on  the  grass, 
and  allowed  to  decay  with  dew  and  rain  falling  upon  them. 
This  is  a  process  which  takes  from  two  to  four  weeks.  Under 
the  system  of  pool-retting,  the  straw  is  immersed  for  about 
ten  days  in  standing  water.  In  some  cases  it  is  preferable 
to  rett  in  running  water  in  a  stream.  Combinations  of  the 
different  methods  are  sometimes  used.  The  fermented 
material  is  then  run  through  a  process  of  breaking  and 
scutching,  combed  out,  and  finally  spun  like  wool  or  cotton. 
Irish  linen  has  the  highest  reputation,  which  is  said  to  be 
due  to  the  slow  bleaching  which  takes  place  from  exposure 
to  the  wet,  pure  air  from  the  Atlantic. 

Jute. — Jute  is  a  native  plant  of  Bengal.  It  requires 
moisture,  and  a  fairly  high  temperature.  It  is  sown  in 
March  to  May,  and  cut  in  four  months'  time,  when  it  is  six 
feet  high.  The  rough  foliage  having  been  removed,  the 
stems  are  removed  in  a  similar  way  to  the  manufacture 
of  linen,  then  beaten,  and  combed  out.  The  crude  jute  is 
packed  into  bales  and  then  exported  for  use  in  sacking  and 
other  rough  purposes.  Jute,  as  a  material  for  cloth,  has 
tended  to  die  out  in  India,  and  has  been  replaced  by  cotton 
materials.  The  lower  parts  of  the  stem  often  make  an 
inferior  type  of  jute,  and  are,  therefore,  commonly  cut  off 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS    127 

and  used  for  rougher  material.  The  crude  material,  on 
arriving  in  this  country,  has  to  undergo  a  certain  amount 
of  treatment  through  sub-divisions  by  a  process  of  combing. 
Jute  fibre  is  a  very  crude  type  of  cellulose,  or,  more  strictly, 
ligno-cellulose,  and  usually  contains  about  10  per  cent,  water 
and  30  per  cent,  matter  soluble  in  acids  and  alkalies. 

Hemp. — Hemp  is  used  chiefly  for  the  production  of 
rope,  and  is  a  very  crude  form  of  cellulose.  Many  different 
plants  are  used  for  the  production  of  hemp,  but  the  chief 
hemp-producing  plant,  Cannabis  sativa,  grows  about  nine 
feet  high,  and  is  treated  like  flax. 

Timber. — A  very  crude  and  imperfect  form  of  cellulose 
constitutes  the  main  structure  of  all  kinds  of  timber.  The 
growth  of  timber  trees  constitutes  the  whole  science  of 
forestry,  a  very  large  subject  indeed.  The  hard  woods, 
like  oak  and  beech,  grow  slowly,  whilst  some  of  the  coniferous 
trees,  such  as  Japanese  larch,  grow  to  a  usable  size  in  twenty- 
five  or  thirty  years.  Timber  is  only  economic  on  very  inferior 
land  or  remote  situations.  Trees  are  generally  felled  in  the 
middle  of  the  summer  or  winter,  to  avoid  felling  them  at 
the  time  when  the  sap  is  moving.  After  felling,  the  logs 
are  sawn  up  into  planks. 

About  1660  a  great  move  was  made  in  planting  timber, 
and  in  1776  Dr.  A.  Hunter  was  able  to  tell  the  Royal 
Society  "there  is  reason  to  believe  that  many  of  the  ships 
which,  in  the  last  war,  gave  laws  to  the  whole  world,  were 
constructed  from  oaks  planted  at  that  time "  (i.e.  1660 
and  thereabouts).  To-day  it  is  our  Army  rather  than  our 
Navy  that  is  so  dependent  on  home-grown  timber,  but  we 
cannot  congratulate  ourselves  on  the  wisdom  of  our  fathers 
as  Dr.  Hunter  did  in  1776.  The  resuscitation  of  home-grown 
timber  production  has  happened  before,  and  it  must  happen 
again. 

Seasoning  timber  is  necessary  to  prevent  warping  after 
use.  Some  form  of  preservative  of  timber  for  building 
purposes  is  often  needed.  Of  these,  creosote  stands  in  the 
front  rank,  and  a  preparation  called  Burnett's  Fluid,  or 
strong  zinc  chloride  solution  (about  50  per  cent.),  is  also  used. 


128  PLANT  PRODUCTS 

It  is  necessary  to  make  the  preservative  enter  well  into  the 
pores  of  the  wood.  If  the  wood  is  at  all  wet,  ordinary 
creosote  fails  to  penetrate,  but  a  solution  of  zinc  chloride 
will  work  under  these  circumstances.  Both  treatments  are 
sometimes  used,  giving  a  blue-purplish  colour  to  the  wood. 
By  adding  to  ordinary  creosote  i  or  2  per  cent,  of  wood  tar, 
and  an  equal  bulk  of  water,  and  adding  enough  sodium 
hydrate  to  make  about  J  per  cent,  of  sodium  hydrate  in  the 
total  mixture,  an  emulsion  can  be  produced  which  will 
penetrate  well  into  any  timber,  even  when  other  methods 
are  unsatisfactory.  These  mixtures  of  soda,  water,  creosote, 
and  wood  tar  can  be  applied  cold,  with  a  brush,  to  common 
larch  and  pine,  giving  a  pleasing  brown  colour  to  fences  and 
outhouses.  Creosote  can  also  be  induced  to  enter  into  well- 
seasoned  wood  by  heating  the  creosote,  or  by  the  use  of 
pressure.  Timber  can  be  kiln  dried  when  time  presses. 

Paper. — Many  of  the  above  types  of  cellulose  can  be 
used  for  the  manufacture  of  paper.  In  former  days,  the 
materials  employed  for  the  manufacture  of  paper  were 
linen,  cotton  rags,  flax  and  hemp.  Now,  however,  wood 
pulp,  bamboo,  straw,  many  rushes,  grass,  peat,  beetroot 
refuse,  potato  stalks,  have  all  found  an  entry  into  the  paper- 
making  industry.  The  potato  stalks  of  town  allotments 
could  be  collected  economically.  I/arge  quantities  of  wild 
grass,  such  as  Soudan  sudd,  are  at  present  unused,  owing  to 
transport  difficulties. 

Mechanical  pulp  is  produced  by  tearing  wood  to  pulp. 
Sulphite  pulp  is  produced  by  treating  wood  with  sulphur 
dioxide  and  water.  The  solution  often  used  is  one  containing 
about  10  per  cent,  of  sulphur  dioxide,  employed  at  a  pressure 
of  about  five  atmospheres  at  100°  Cent.  Disintegration 
takes  about  twelve  hours,  more  or  less,  according  to  the 
nature  of  the  wood. 

The  miscellaneous  materials  which  can  be  put  to  the 
making  of  paper  have  first  of  all  to  be  disinfected,  then  cut 
into  small  pieces,  and  run  through  special  cutting  machines. 
To  remove  greasy  matters,  the  materials  are  boiled  with 
a  solution  of  caustic  soda  and  caustic  lime.  L,inen  rags  will 


THE  CA RBOHYDRA  TES  PROD UCED  IN  CROPS  129 

often  lose  from  one-third  to  one-fifth  of  their  weight  through 
the  process  of  boiling,  whilst  inferior  materials  will  lose  much 
more.  After  being  boiled,  the  material  is  washed,  and  broken 
up,  so  as  to  disintegrate  all  the  fibres.  When  the  materials 
used  for  paper  -  making  require  bleaching,  chlorine  gas, 
bleaching  powder  or  electrolyzed  magnesium  chloride  is 
used.  The  first  named  is  the  least  satisfactory,  and  the  last 
the  best.  The  paper  pulp  is  then  separated  from  the  water 
by  some  kind  of  sieve.  Under  old-fashioned  systems  this 
was  often  done  by  hand,  but  it  is  now  mostly  done  by 
continuous  machines,  which  separate  the  paper  pulp  from 
the  liquors,  often  with  the  aid  of  a  certain  amount  of  suction, 
produced  by  a  pump.  The  paper  is  rolled  by  rollers,  some- 
times with  the  aid  of  steam  heat. 

Destructive  Distillation  of  Cellulose. —All  forms 
of  cellulose,  when  destructively  distilled,  produce  char 
coal,  tar,  acetic  acid,  water,  gas,  and  a  few  other  special 
products.  The  crude  forms  of  cellulose  commonly  used  for 
this  process  introduce  many  other  substances  in  small 
amounts.  The  form  of  cellulose  most  commonly  used  for 
this  distillation  is  some  form  of  wood  which  is  no  longer 
useful  for  other  purposes.  In  felling  timber  the  amount 
of  wood  useless  for  any  of  the  purposes  to  which  timber  is 
commonly  put  will  generally  exceed  in  weight  that  of  the 
useful  material.  Probably  each  1000  acres  of  wood  produce 
forty  tons  per  annum  of  woody  material  of  no  value  for 
ordinary  purposes,  much  of  which  can  be  destructively 
distilled  and  converted  into  useful  products.  The  distillation 
of  these  materials  can  be  divided  into  two  separate  systems, 
that  in  which  the  wood  is  brought  to  the  still,  and  that  in 
which  the  still  is  taken  to  the  wood.  Where  it  is  possible 
to  convey  the  wood  to  the  still,  the  still  can  be  constructed 
of  fairly  large  dimensions.  The  best  of  these  systems 
needs  a  large  retort,  eight  or  ten  feet  in  diameter,  and  fifty 
or  one  hundred  feet  long.  Two  or  more  of  these  are  set 
in  a  big  setting,  and  heated  with  flue  gases  from  furnaces. 
The  temperature  in  the  flues  should  be  between  400°  and 
500°  Cent,,  and  the  escaping  products  of  combustion  will 

D.  9 


130  PLANT  PRODUCTS 

be  200°  and  250°  Cent.,  so  that  considerable  loss  of  heat 
occurs  unless  some  means  of  utilization  is  devised.  The 
wood  is  placed  in  trucks  and  run  into  the  retorts.  If  the 
wood  is  fairly  dry,  25  per  cent,  of  charcoal  will  be  left  behind. 
The  charcoal  is  preferably  rapidly  transported  in  trucks  to 
a  cooling  chamber,  which  is  often  externally  cooled  by  sprays 
of  water.  When  cold,  the  charcoal  is  placed  in  store.  The 
products  of  distillation  are  passed  through  a  fractionating 
arrangement,  which  causes  the  condensation  of  the  heavier 
tars,  and  then  through  an  ordinary  form  of  condenser, 
where  other  substances  condense.  The  gas  passing  away 
contains  considerable  quantities  of  carbon  monoxide,  which 
is  burnt  in  the  fire  and  assists  in  maintaining  the  temperature. 
The  tar  which  is  separated  in  the  tar  separator  is  boiled  to 
drive  off  the  water  which  it  still  contains.  The  portion  of 
the  distillate  from  which  the  tar  has  been  removed,  commonly 
called  pyro-ligneous  acid,  is  then  distilled,  to  remove  the 
acetone  and  methyl  alcohol,  which  are  subsequently 
fractionated  into  pure  products,  with  a  still  of  somewhat 
similar  type  to  that  used  in  all  industrial  concerns  for 
fractionation  of  volatile  substances.  The  remaining  acid  is 
then  treated  with  lime,  at  the  rate  of  about  four  pounds  per 
ten  gallons  liquor,  when  a  heavy  black  sludge  is  thrown  out, 
consisting  of  any  excess  lime  and  compounds  of  the  lime  with 
higher  acids  of  the  acetic  series  and  polymerized  forms  of 
aldehydes.  After  settling  for  some  days,  the  clear  liquid  is 
removed,  boiled  down,  and,  when  nearly  dry,  run  over  heated 
rollers  to  obtain  the  acetate  of  lime  in  a  fine,  dry  state.  Many 
attempts  have  been  made  to  produce  a  continuous  apparatus, 
but  such  are  only  suited  to  small  wood.  Small  vertical  retorts 
also  deal  very  efficiently  with  small  wood.  A  very  excellent 
article  on  this  subject  is  found  in  Thorpe's  "Dictionary  of 
Applied  Chemistry,"  under  the  title  of  "  Wood."  Where 
the  wood  is  scattered  over  large  areas,  it  is  necessary  to 
bring  the  still  to  the  wood,  rather  than  the  reverse.  For 
this  purpose  a  portable  plant  has  been  designed  by  the  author 
(see  Bibliography).  A  portable  machine  of  the  type 
described  will  consume  nearly  all  the  waste  wood  of  about 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS     131 

3000  acres  ordinary  timber.  It  would  also  serve  the  purpose 
of  any  moderate-sized  works  dealing  with  about  150  to  600 
tons  of  waste  wood  per  annum,  according  to  whether  the 
machine  was  worked  continuously  or  not.  With  small 
plants  it  is  quite  impractical  to  attempt  to  conserve  the 
acetone  and  methyl  alcohol.  For  the  purpose  of  obtaining 
charcoal,  however,  small  forms  are  more  economical.  The 
old-fashioned  method  of  burning  charcoal  in  heaps  (see 
Bibliography)  produces  a  charcoal  with  a  high  percentage  of 
ash,  which  for  many  industrial  purposes  is  extremely  objec- 
tionable. Distillation  in  retorts  produces  a  purer  charcoal, 
but  for  the  purpose  of  obtaining  a  charcoal  with  little  ash 
larger  pieces  of  wood  only  should  be  carbonized.  For  the 
preparation  of  high-class  charcoal  for  industrial  purposes  a 
small  plant  is,  therefore,  more  manageable,  as  it  can  be  used 
to  produce  charcoal  of  any  particular  kind.  For  annealing 
or  case-hardening  steel  a  charcoal  powder  containing  a  high 
percentage  of  volatile  matter  is  preferred.  Where  this 
is  the  case,  the  temperature  of  distillation  must  be  kept 
below  that  stated  above.  Where  a  dense  charcoal  is  required, 
long  protracted  heating  is  necessary.  For  average  conditions 
the  period  of  distillation  will  occupy  three  or  four  hours  for 
each  foot  in  the  diameter  of  the  retort.  With  small  laboratory 
size  retorts  distillation  can  take  place  in  under  half  an  hour, 
but  in  large  retorts  running  up  to  eight  feet  in  diameter  two 
days  will  be  found  necessary.  Bigger  retorts  than  this  are 
not  practicable.  Small  pieces  of  wood  distil  distinctly  more 
quickly  than  large  pieces.  When  coniferous  wood  is  distilled, 
a  valuable  product  is  turpentine.  A  ton  of  hard  wood  on 
distillation  gives  about  eighteen  gallons  of  water  with  little 
acid  in  the  first  fraction,  which  is  hardly  worth  saving, 
and  thirty  gallons  of  strong  pyro-ligneous  acid  in  the  second 
fraction.  The  economy  in  treatment  by  this  fractionation 
compensates  for  some  of  the  disadvantages  of  an  intermittent 
machine. 

Charcoal  from  coconut  shells  has  a  high  absorptive 
power  for  gases  or  vapours. 

(d)  Gum  and  Mucilage. — The  name  "  gum  "  is  a  general 


132  PLANT  PRODUCTS 

term  for  a  large  group  of  plant  products,  which  are  exuded 
by  wounds  and  are  transparent.  Gum  arable,  obtained  from 
the  various  species  of  acacia,  is  one  of  the  best  of  these.  The 
gum  is  obtained  by  artificial  incision  of  <the  trees,  soon  after 
the  end  of  the  rainy  season  and  is  collected  at  intervals 
of  every  few  days,  so  long  as  the  weather  permits.  Trees 
of  about  eight  to  twelve  years  of  age  are  usually  the  most 
productive.  Bast  Indian  gum  arabic,  though  shipped  from 
Bombay,  is  very  often  not  produced  in  India,  but  has  been 
collected  in  other  parts  and  transported  to  Bombay  for 
shipment.  Australian,  or  wattle-gum,  is  a  product  of 
several  specis  of  acacia,  called  by  the  local  name  of  wattle. 
Gum  is  much  more  soluble  in  hot  than  in  cold  water,  forming 
a  thick  liquid,  and  is  precipitated  by  alcohol  or  lead  acetate. 
Although  the  gums  are  commonly  included  in  the  carbo- 
hydrate group,  their  constituents  are  by  no  means  pure 
carbohydrate.  The  chief  constituent  of  gum  arabic  is 
arabin,  which,  on  hydrolysis,  yields  arabinose,  galactose,  and 
an  acid  of  high  molecular  weight,  C23H38O22,  arabic  acid. 

Agar. — Agar  gum,  the  dried  jelly  of  seaweed,  is  chiefly 
obtained  from  China  and  Japan,  but  is  very  plentiful  where 
there  is  plenty  of  seaweed.  The  special  gum  contained  is 
known  as  gelose,  which  is  soluble  in  water,  weak  alcohol,  and 
alkalies.  Kven  a  solution  of  }  per  cent,  of  agar  is  faiily 
solid  in  ordinary  temperatures.  Seaweed,  when  boiled  with 
water,  forms  the  nucleus  of  many  articles  of  food  used  in 
Cornwall  and  in  Japan.  It  is,  however,  not  easily  digested, 
but  is  useful,  admixed  with  milk,  in  preventing  the  formation 
of  a  hard  curd  in  the  stomach. 

Mucilage.  —Many  seeds  of  plants,  for  example  linseed, 
when  macerated  with  water,  produce  a  thick  adhesive 
mucilage  which  can  be  used  in  place  of  gum. 


REFERENCES  TO  SECTION  II,  A  (SUGAR) 

Collins,  "  Value  of  the  Turnip  as  a  Vegetable  and  Stock  Food,"  Journ. 
Board  of  Agriculture,  1916-17,  p.  66. 

Collins,  "  Variation  in  the  Chemical  Composition  of  the  Swede,"  Journ. 
Agric.  Science,  i.,  p.  89. 


THE  CARBOHYDRATES  PRODUCED  IN  CROPS  133 

Collins.  "  The  Relative  Amounts  of  Dry  Matter  in  Several  Varieties 
of  Swedish  Turnips,"  Proc.  Univ.  Durham  Phil.  Soc.,  vol.  iii.,  p.  303. 
(Andrew  Reid,  Newcastle-on-Tyne.) 

Hendrick,  "  The  Composition  of  Turnips  and  Swedes,"  Trans.  Highland 
and  Agricultural  Soc.,  Scotland,  1906. 

Collins,  "  Sugar  in  Swedes,"  Journ.  Soc.  Chem.  Ind.,  1901,  p.  536;  1902, 

P-  1513- 

Wood  and  Berry,  "  A  Rapid  Method  of  Estimating  Sugar,"  Proceedings 
of  the  Cambridge  Philosophical  Society,  vol.  xii.,  part  ii.,  p.  112. 

Denbigh,  "  Beet  Sugar  as  a  British  Industry,"  p.  21.  (The  National 
Sugar  Beet  Association,  Ltd.) 

Leather,  "  Memoirs  of  the  Department  of  Agriculture  in  India,"  Oct., 
1913,  p.  113.  (Thacker  and  Co.) 

Home  Counties,  "  Sugar  Beet,"  p.  5.     (Horace  Cox.) 

Leather  and  Mollison,  "  The  Agricultural  Ledger,"  1898,  No.  8,  p.  2. 
(Government  Central  Press,  Bombay.) 

Aubert,  "The  Manufacture  of  Palm  Sugar,"  Agric.  Journ.  Ind.,  1911, 
p.  369. 

Martineau,  "  Sugar,"  p.  41.     (Pitman.) 

Higgins,  "  Observations  and  Advices  for  the  Improvement  of  the 
Manufacture  of  Muscado  Sugar  and  Rum,"  p.  9.  (Aikman.) 

Mackenzie,  "  The  Sugars  and  their  Simple  Derivatives,"  p.  12.    (Garney.) 

Collins  and  Hall,  "  The  Composition  of  Sugar  Beets  Grown  in  the 
Northern  Counties,"  Journ.  Soc.  Chem.  Ind.,  1913,  p.  929. 

"Discussion  on  Production  and  Refining  of  Sugar  within  the  Empire," 
Journ.  Soc.  Chem.  Ind.,  1915,  p.  316. 

Potvliet,  "  The  Beet  Sugar  Industry  in  Canada,"  Journ.  Soc.  Chem.  Ind., 
1916,  p.  443. 

Orwjn  and  Orr,  "  The  Cultivation  of  Sugar  Beet  in  the  West  of  Ireland," 
Journ.  Board  of  Agriculture,  1915-16,  p.  210;  do.  in  Norfolk  and  Suffolk, 
1914-15,  p.  969. 

Leather,  "  Manuring  Sugar  Cane,"  Agric.  Journ.  India,  1906,  p.  13. 

Barber,  "  Sugar  Cane  Cultivation  in  Godavari,"  Agric.  Journ.  India, 
J907,  p.  33. 

Chadwin,  "  The  Cantley  Beet  Sugar  Factory,  "Journ.  Board  Agriculture, 

1913-14.  P-  569- 

Dowling,  "  The  Production  of  Beet  Sugar  in  a  Continental  Factory," 
Journ.  Board  Agriculture,  1911-12,  p.  1005. 

REFERENCES  TO  SECTION   II,   B   (STARCH) 

Haas  and  Hill,  "  The  Chemistry  of  Plant  Products,"  p.  93.  (Longmans 
and  Co.) 

Radhakamal  Mukerjee,  "  The  Foundations  of  Indian  Economics." 
(Longmans  and  Co.) 

Archbold,  "  The  Manufacture  of  Maize  Starch,"  Journ.  Soc.  Chem.  Ind., 
1902,  p.  4. 

Dyer  and  Shrivell,  "  The  Manuring  of  Market-Garden  Crops,"  p.  92. 
(Vinton.) 
•  Wallace,  "  Indian  Agriculture,"  p.  203.     (Oliver  and  Boyd.) 

Wiley,  "  The  Manufacture  of  Starch  from  Potatoes  and  Cassava." 
(Government  Printing  Office,  Washington.) 

Howard,  "  Wheat  in  India."     (Thacker.) 

Church,  "  The  Food  Grains  of  India."     (Chapman.) 

Gilbert,  "  The  Potato."     (Macmillan.) 

REFERENCES   TO   SECTION   II,   C   (CELLULOSE) 

Hall  and  Russell,  "  Agriculture  and  Soils  of  Kent,  Surrey  and  Sussex," 
p.  50.  (Board  of  Agriculture  and  Fisheries.) 


134  PLANT  PRODUCTS 

Watt,  "  The  Art  of  Paper-Making."     (Crosby  Lockwood  and  Son.) 

"Flax  Growing,"  Journ.  Board  Agriculture,  1914-15,  p.  1007. 

Tom,  "  Department  of  Agriculture  and  Technical  Instructions,  Ireland," 
1914,  p.  515. 

Nystron,  "  Textiles,"  pp.  38  and  112.     (Appleton.) 

Benson  and  Davis,  "  Free  Carbon  of  Wood-Tar  Pitches,"  Analyst, 
June,  1917,  p.  212. 

Wallace,  "  Indian  Agriculture,"  pp.  203,  247.     (Oliver  and  Boyd.) 

Roberts,  "  Bark  Stripping,"  Journ.  Land  Agents'  Soc.,  July,  1908,  p.  314. 

Collins,  "  A  Portable  Plant  for  the  Distillation  of  Wood,"  Journ. 
Soc.  Chem.  Ind.,  1917,  p.  68. 

Collins  and  Hall,  "  The  Use  of  Coal  Tar  Creosote  and  Naphthalene  for 
Preserving  Wooden  Fences,"  Journ.  Soc.  Chem.  Ind.,  1914,  p.  466. 

"The  Manufacture  of  Charcoal,"  Journ.  Board  Agriculture,  1914-15,  p. 

i°33- 

Rowley,  "  The  Commercial  Utilization  of  the '  Grass  Tree  '  (Xanthorrhcea) 
and  '  Zamia  '  (Macrozamia)  in  Western  Australia,"  Journ.  Soc.  Chem.  Ind., 
1916,  p.  290. 

Briggs,  "  Some  Causes  of  Damage  in  the  Bleaching  of  Linen  and  Cotton 
Textiles,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  78. 

Briggs,  "  The  Paper  Mill  Chemist  in  War  Time,  "Journ.  Soc.  Chem.  Ind., 

1916,  p.  798. 

Cross,  "  Cellulose  and  Chemical  Industry,"   Journ.    Soc.  Chem.   Ind., 

1917.  P-  53i- 

Klason,  Heidstam  and  Norlin,  "  Dr}'  Distillation  of  Cellulose,"  Journ. 
Chem.  Soc.,  1908,  A.  i,  p.  717. 

Klason,  Heidstam  and  Norlin,  "  Investigations  on  the  Charring  of  Wood," 
Journ.  Chem.  Soc.,  1908,  A.  i,  p.  955. 

Boulton,  "Antiseptic  Treatment  of  Timber,"  Journ.  Soc.  Chem.  Ind., 
1884,  p.  622. 

Fletcher,  "  Improvement  of  Cotton,"  Agric.  Journ.  India,  1906,  p.  351. 

Stebbing,  "  British  Forestry."     (Murray.) 

"Some  Douglas  Fir  Plantations,"  Journ.  Board  Agriculture,  1913-14, 
p.  1087. 

Coventry,  "  Rhea  Experiments  in  India,"  Agric.  Journ.  India,  1907,  p.  i. 

Smith,  "  Jute  Experiments  in  Bengal,"  Agric.  Journ.  India,  1907,  p.  140. 

Ellmore  and  Okey,  "  Osier  and  Willow  Cultivation,"  Journ.  Board  of 
Agriculture,  1911-12,  pp.  12,  207,  557,  906. 

Somerville,  "  Increasing  the  Durability  of  Timber,"  Journ.  Board  of 
Agriculture,  1911-12,  p.  283. 

REFERENCES  TO   SECTION   II,   D   (GUM) 

O'Sullivan,  "  Gum  Tragacanth,"  Journ.  Chem.  Soc.,  1901,  T.  1164. 
Schryver   and   Haynes,    "  Pectic    Substances   of    Plants,"    Biochem. 
Journ.,  1916,  p.  539. 

Imperial  Institute  Report,  "  Gums  and  Resins." 


SECTION  III.— THE  FORMATION   OF  OILS 
IN  PLANTS 

Linseed. — I/inseed  has  already  been  described  under  the 
subject  of  linen  (p.  126),  but  it  is  also  used  for  the 
production  of  an  oil  seed.  Where  the  plant  is  grown  in 
cold,  damp  climates,  the  situation  favours  the  production 
of  fibre,  but  where  it  is  grown  in  drier  and  warmer  districts 
the  situation  favours  the  production  of  seed.  It  can  be 
grown  in  many  countries,  but  the  chief  sources  of  linseed 
are  Russia,  India,  and  the  Argentine.  I/inseed  contains 
about  35  per  cent,  of  oil,  which  is  expressed  both  on  the  large 
and  on  the  small  scale.  When  linseed  is  imported  into  Great 
Britain  it  is  generally  first  of  all  cleaned  from  its  miscellaneous 
impurities,  often  amounting  to  10  per  cent.,  and  the  purified 
linseed  run  through  rollers  to  crush  it  without  actually 
expressing  oil.  It  is  then  passed  through  a  "  kettle,"  where 
it  is  subjected  either  to  direct  steam  heat,  or  to  the  heat 
from  steam  passing  through  a  coil,  or  both.  I/inseed  grown 
in  India  is  very  dry,  and  requires  the  moisture  content 
to  be  increased,  which  is  conveniently  done  by  blowing  steam 
into  it.  lyinseed  obtained  from  the  Baltic  ports  is  some- 
times rather  too  damp  for  the  process,  and  the  steam  is, 
therefore,  passed  through  a  coil,  so  as  to  both  heat  and  slightly 
dry  the  linseed.  The  linseed  is  then  placed  between  felts 
which  are,  in  turn,  placed  between  corrugated  iron  sheets, 
which  are  built  up  into  a  pile  of  twenty  or  thirty  in  a  hydraulic 
press.  The  name  "hydraulic  press  "  is  here  somewhat  of  a 
misnomer,  because  in  practice  the  liquor  used  in  the  pumps 
is  not  water,  but  the  oil  which  is  being  produced  at  the  time. 
If  water  were  used,  any  leak  in  the  press  would  damage  the 
oil,  but  when  the  oil  itself  is  used  this  is  not  possible.  As 


136  PLANT  PRODUCTS 

soon  as  the  pressure  is  applied  the  oil  begins  to  run  out,  and 
is  collected  in  a  well.  On  long  standing,  small  quantities 
of  mucilage  are  formed  in  the  oil.  For  the  best  qualities 
of  oil  the  crude  oil  is  filtered.  I^inseed  can  be  extracted 
with  petroleum  spirit,  but  it  is  very  rarely  treated  in  this 
way,  because  linseed  cake  rich  in  oil  has  a  high  value  as 
cattle  food. 

Dark  linseed  oil  is  commonly  refined  by  treatment  with 
sulphuric  acid.  The  refined  oil  is  also  subjected  to  sun 
bleaching  in  some  cases.  linseed  oil,  in  addition  to  the 
ordinary  fatty  acids,  contains  linoleic  and  linolenic  acids. 
Linseed  oil  has  a  high  iodine  value,  and  is  a  drying  oil 
occupying  the  first  rank.  Boiled  oil  is  obtained  by  heating 
linseed  oil  to  a  temperature  of  about  150°  Cent.,  with  the 
addition  of  driers,  which  often  contain  manganese  and  lead. 
Linseed  oil  is  also  vulcanized  by  sulphur  chloride  to  form  a 
rubber  substitute  (see  p.  165). 

The  remaining  linseed  cake  as  it  comes  out  of  the  press 
is  still  somewhat  warm,  and  is  sometimes  dipped  in  water, 
to  give  the  cakes  a  bloom.  It  is  then  sold  for  cattle  food. 
Under  ordinary  farm  conditions,  where  the  chief  .part  of  the 
home-grown  food  consists  of  hay,  straw,  turnips,  and  tail 
corn,  the  purchase  of  a  food  containing  some  oil  is  highly 
desirable,  and  linseed  is  one  of  the  most  popular  of  these 
materials.  linseed  cakes  generally  contain  about  1 1  per  cent, 
of  oil,  rather  less  in  those  of  American  manufacture,  rather 
more  in  those  of  Russian  origin,  about  32  per  cent,  of 
albuminoids,  rather  more  in  cakes  of  American  origin,  and 
rather  less  in  cakes  of  Indian  origin,  and  do  not  contain 
more  than  about  7  per  cent,  of  fibre.  I^inseed  cake  is  reckoned 
as  one  of  the  safest  of  cattle  foods,  and  is  a  favourite  for 
rearing  calves  on.  lyinseed  contains  a  cyano-genetic 
glucoside  called  linimarin,  which,  by  the  action  of  the  proper 
enzyme,  contained  in  the  linseed,  will  develop  prussic  acid, 
acetone,  and  glucose  under  certain  conditions.  If  ground 
linseed  cake  be  placed  in  water  at  temperatures  between 
20°  and  60°  Cent.,  the  action  of  the  enzyme  on  the  linimarin 
will  begin.  The  rate  at  which  the  prussic  acid  is  evolved 


THE  FORMATION  OF  OILS  IN  PLANTS    137 

depends  upon  a  variety  of  circumstances,  which  are  not  very 
likely  to  occur  under  ordinary  conditions  of  feeding,  but  which 
may  be  found  when  the  feeding  is  conducted  on  careless 
lines.  It  happens  that  linseed  grown  in  hot  climates  contains 
more  poison  than  linseed  grown  in  Great  Britain,  but  since 
it  is  also  drier,  the  manufacturer  uses  steam  before  pressing 
it,  thus  undesignedly  counteracting  the  poison.  The  extent 
to  which  this  takes  place  varies  according  to  the  details 
of  manufacture  in  the  works  concerned.  There  is  extremely 
little  risk  of  adult  animals  in  good  health  being  poisoned. 
So  long  as  the  seed  is  fed  whole,  or  only  simply  crushed, 
there  is  little  risk  of  poison  being  formed,  but  if  linseed  cake 
in  the  form  of  fine  meal  is  partly  mixed  with  warm  water, 
it  remains  in  the  form  of  small  balls.  Calves,  if  fed  with 
such  badly  made  linseed  mash,  do  not  properly  chew  the 
balls,  but  swallow  them  whole,  so  that  they  break  up  in  the 
stomach  and  liberate  the  prussic  acid.  Where  linseed,  or 
linseed  meal,  is  actually  boiled  with  water,  the  enzyme  is 
completely  destroyed.  Once  the  enzyme  has  been  checked 
by  the  action  of  acid  or  alkali  it  is  not  able  to  recover  its 
old  vigour.  A  degree  of  acidity  equal  to  10*00  normal 
hydrochloric  acid  is  sufficient  to  check  the  activity  of  the 
enzyme.  Where  care  is  taken  in  the  preparation  of  the 
meal  no  poisoning  cases  arise.  linseed,  like  most  of 
the  oil  seeds,  contains  no  starch. 

Cotton.  — The  growth  of  the  cotton  plant  has  been  already 
described,  and  its  use  for  the  manufacture  of  fibre  (p.  125). 
After  the  cotton  fibre  has  been  removed  from  the  seeds,  the 
latter  form  a  valuable  part  of  the  crop.  L,ike  linseed,  cotton 
seed  is  rich  in  oil,  containing  about  30  per  cent.,  although 
some  varieties,  especially  those  of  Indian  origin,  are  all 
lower  in  their  oil  content.  Oil  obtained  from  fresh  seed 
is  paler  in  colour  than  that  from  old  seed,  but  the  latter  is 
clarified  by  washing  with  caustic  soda  and  cooling  till 
stearin  separates  out.  Cotton-seed  oil  is  not  a  drying  oil, 
like  linseed,  and  is  used  for  lubricating  purposes,  and  for 
replacing  olive  oil,  butter,  and  other  edible  fats. 

Owing  to  the  large  amount  of  husk  enclosing  the  cotton 


138  PLANT  PRODUCTS 

seeds,  the  fibre  amounts  to  18  per  cent.  Two  systems  of 
pressing  the  cakes  have  arisen,  (i)  Where  the  seed  is 
pressed  whole,  the  husk  remains  in  the  cake,  and  whilst 
it  provides  a  good  channel  for  the  escape  of  the  oil,  it  acts 
as  an  absorbent,  and  prevents  some  of  the  oil  flowing  out. 
(2)  Where  the  husk  is  removed,  a  lower  pressure  suffices, 
but  it  is  not  possible  to  leave  the  cake  with  as  low  a  percentage 
of  oil.  There  are,  consequently,  many  types  of  cotton  cake 
put  upon  the  market.  The  Indian  cotton  cakes  derived  from 
seed  grown  in  India  and  pressed  in  England  usually  contain 
about  4^  per  cent,  of  oil,  19  per  cent,  of  albuminoids,  and  21 
per  cent,  of  fibre,  and  are  often  dirty  and  sandy.  The  short 
fluff  remaining  on  the  seed  hinders  cleaning  previous  to 
pressing.  Most  Egyptian  cotton  cakes  contain  about  5  per 
cent,  of  oil,  23  per  cent,  of  albuminoids,  and  19  per  cent, 
of  fibre,  and  have  a  somewhat  higher  feeding  value  than 
Indian  cakes.  Decorticated  cotton  cakes  are  produced 
in  America  by  lemoving  the  husks  of  the  seed  previous  to 
pressure.  These  usually  contain  n  per  cent,  of  oil,  40  per 
cent,  of  albuminoids,  and  8  per  cent,  of  fibre,  but  great 
variations  occur.  Where  these  cakes  are  extracted  by 
petroleum  spirit  the  percentage  of  oil  is  reduced,  and  where 
the  decortication  is  indifferently  performed  the  fibre  may 
rise  to  15  per  cent.  At  one  time  there  was  a  habit  of  treating 
Indian  cotton  cakes  with  small  quantities  of  borax,  for  the 
purpose  of  preventing  fermentation  and  subsequent  dis- 
coloration. The  fashion,  however,  appears  to  be  dying  out. 
The  Soy  Bean. — The  soy  bean  is  grown  very  largely 
in  Japan  and  Manchuria,  as  well  as  in  other  parts  of  the  world. 
Many  crops  of  soya-bean  seeds  only  contain  16  per  cent,  of 
oil.  The  oil  is  pressed  in  the  same  way  as  the  other  oil  seeds 
named  above,  and  the  resulting  cake  contains  about  6  per 
cent,  of  oil,  42  per  cent,  of  albuminoids,  and  5  per  cent, 
of  fibre.  Soya-bean  oil  belongs  to  the  drying  class  of  oils, 
but  it  is  not  equal  to  linseed  in  this  respect.  The  cake 
remaining  is  a  particularly  palatable  one,  and  much  appreci- 
ated by  all  cattle.  The  bean  itself  is  frequently  used  for 
human  food  in  the  East,  and  experiments  are  being  made  to 


THE   FORMATION  OF   OILS  IN  PLANTS     139 

grow  soy  beans  in  Australia,  South  Africa,  the  United  States, 
Italy,  Spain,  South  America,  and  even  in  the  British  Isles. 
In  the  crude  preparation  of  the  oil  in  Manchuria  the  beans 
are  soaked  in  water  over-night,  crushed,  and  boiled  with 
water,  so  that  the  oil  cells  are  broken.  The  oil  is  then 
expressed  in  a  very  primitive  press.  In  spite  of  the  primitive 
character  of  this  method  of  preparation,  as  much  as  13  per 
cent,  of  oil  is  said  to  be  expressed,  at  the  expenditure  of 
much  labour  and  time,  whilst  modern  machinery  rarely 
succeeds  in  extracting  more  than  12  per  cent. 

Palm  Nuts  and  Coconuts. —The  coconut  palm  is  a 
tree  growing  to  a  considerable  height,  chiefly  inhabiting 
the  sea-coasts  of  the  tropical  regions.  It  is  propagated  from 
the  nuts  in  nurseries  and  planted  out.  About  7  tons  of 
coconuts  can  be  obtained  per  acre  of  plantation.  The 
coconut  is  dehusked  and  dried,  and  the  resulting  material, 
known  as  copra,  is  expressed  for  its  oil.  The  palm  kernels 
contain  nearly  50  per  cent,  of  oil.  The  oil  so  obtained  from 
the  palm  nuts  or  the  coconuts,  on  cooling,  throw  out  much 
solid  material,  which  can  be  used  for  the  manufacture  of 
margarine  or  soap.  The  remaining  cakes  are  of  the  following 
composition.  The  coconut  cakes  vary  from  about  7  to 
12  per  cent,  of  oil,  from  19  to  22  per  cent,  of  albuminoids, 
and  10  to  13  per  cent,  of  fibre,  whilst  the  palm  nut  cakes 
vary  from  about  7  to  10  per  cent,  of  oil,  from  about  17  to 
21  per  cent,  of  albuminoids,  and  n  to  16  per  cent,  of  fibre. 
The  palm  kernels  are  not  infrequently  extracted  with 
petroleum  spirit,  in  which  case  the  oil  in  the  residue,  which 
is  often  sold  as  palm  kernel  meal,  is  as  low  as  i  to  3  per  cent, 
of  oil.  Whilst  coconut  and  palm  nut  cakes  and  oils  have  a 
considerable  degree  of  resemblance,  there  are  some  points 
which  differentiate  them,  both  in  their  history  and  in  the 
character  of  their  products.  The  coconut  has  been  known 
since  the  earliest  times  as  a  food  material  in  India,  and  the 
South  Sea  Islands.  When  unripe  they  are  often  used  as 
drinking  coconuts — that  is,  they  are  removed  from  the  trees 
in  the  green  condition,  the  top  sliced  off,  and  the  "  milk," 
which  looks  more  like  ginger  beer,  drunk  from  the  shell. 


140  PLANT  PRODUCTS 

For  the  preparation  of  oil  the  primitive  system  consisted  in 
removing  the  husk,  cutting  up  the  kernel  into  small  pieces, 
exposing  in  piles  to  the  heat  of  the  sun,  so  that  the  oil  ran 
off  and  was  collected.  Another  method  was  that  of  pulping 
the  kernels  and  placing  them  in  a  kind  of  sieve  exposed  to 
the  sun,  when  the  oil  ran  off  and  was  collected.  Sometimes 
artificial  heat  was  used.  In  India  the  dried  kernels  were 
ground  in  the  primitive  oil  press,  or  were  thrown  into 
boiling  water  and  the  oil  skimmed  off.  The  residues  were  often 
used  locally  for  cattle  food.  The  dried  husk,  known  as 
copra,  is  liable  to  ferment,  due  to  the  presence  of  water,  and 
many  of  the  difficulties  of  manufacture  and  the  prejudice 
against  the  materials  resulted  from  this  cause.  Modern 
systems  eliminate  much  of  this  difficulty,  by  first  removing 
the  fibrous  matter  (coir)  and  then  striking  the  nut  on  a 
sharp  spike.  The  husk  is  removed  by  hand  and  the  nut  split, 
drained  and  put  in  the  sun  to  dry.  Sun-dried  copra  gives 
better  quality  oil  than  that  which  has  been  dried  in  kilns, 
but  improvements  in  the  kiln  system  of  drying  are  likely 
to  remove  this  difficulty.  The  coconut  shells  are  used  for 
firing  the  kilns  (see  p.  131).  In  the  modern  system  of 
pressure,  two  pressings  are  carried  out,  the  temperatures 
adopted  being  higher  than  those  used  for  linseed  as  described 
above.  About  65  per  cent,  of  oil  can  be  obtained  from  the 
best  qualities  of  copra.  Owing  to  the  fermentive  changes 
alluded  to  above  it  is  not  infrequent  for  considerable  quantities 
of  free  fatty  acid  to  be  present  in  the  oil,  but  the  great  care 
taken  in  modern  manufacture  tends  to  reduce  this  degree 
of  acidity.  Owing  to  its  high  melting  point,  coconut 
oil  is  not  infrequently  met  with  in  the  solid  or  semi-solid 
condition.  Although  coconut  oil  requires  a  high  strength 
of  alkali  and  high  temperature  for  saponification,  yet 
with  alkali  of  the  right  strength  soap  is  formed  at  ordinary 
temperatures.  Soap  made  from  coconut  oil  is  soluble  in 
weak  salt  solutions  and  is  used  for  washing  in  sea-water. 
Although  this  confers  an  advantage  in  certain  uses  of  the 
soap,  it  compels  the  manufacturer  to  employ  more  salt 
to  throw  soap  out  of  solution  in  the  boiling  vat. 


THE   FORMATION  OF  OILS  IN  PLANTS    141 

The  oil  palm  tree,  which  gives  the  palm  kernel  oil,  more 
frequently  grows  inland  in  open  country  and  bush  land,  in 
contradistinction  to  the  coconut,  which  grows  chiefly  on 
the  sea  border.  Neither  trees  are  commonly  met  with  at  any 
considerable  altitude.  The  rough  method  by  which  the 
palm  nuts  are  collected  causes  much  injury  to  the  kernels 
and  results  in  subsequent  hydrolysis  of  the  oil.  The  outer 
layer  of  the  fruit  is  removed  for  making  palm  oil,  and  the 
nuts  are  shelled.  In  the  rough  preparation  the  kernels 
are  often  fermented  before  pressing,  which  also  causes  the 
same  difficulty  alluded  to  above  in  coconut  oil.  The  rough 
purification  of  this  crude  oil  is  often  carried  out  by  boiling 
up  with  water.  Palm  oils  not  infrequently  have  as  high 
as  one  half  of  their  total  amount  of  fatty  acids  in  the  free 
condition,  accompanied,  of  course,  by  the  corresponding 
amount  of  free  glycerine.  In  recent  years  the  palm  kernels 
have  been  brought  into  Great  Britain  and  have  been  pressed 
in  home  machinery  of  modern  type.  The  result  has  been 
that  much  superior  oils  have  been  obtained,  with  far  less 
free  fatty  acids,  and  the  resulting  oil  cakes  have  also  been 
superior.  The  oil  is  mostly  used  for  soap,  candles,  and 
margarine.  Whilst  many  of  the  early  makes  of  both  cakes 
were  distinctly  rancid,  yet  the  modern  cakes  are  relatively 
free  from  this  objection.  Nevertheless,  cattle  do  not  take 
kindly  to  either  of  these  cakes  at  first.  It  is  usually  less 
difficult  to  persuade  cattle  to  eat  coconut  cake  than  palm- 
nut  cake.  When  coconut  cake  has  been  only  slightly 
pressed  it  is  very  apt  to  absorb  moisture  so  readily  as  to  break 
itself  up  and  burst  the  sacks  in  which  it  has  been  placed. 
As  much  as  10  per  cent,  of  water  may  easily  be  absorbed  by 
such  cake  when  standing  in  ordinary  barns  on  the  farmstead. 
As,  however,  this  difficulty  has  become  recognized,  and  as  the 
oil  is  very  valuable,  manufacturers  are  now  usually  taking 
greater  care  to  press  the  cakes  more  completely,  and  they 
are  thereby  producing  a  bigger  yield  of  oil  and  at  the  same 
time  a  cake  which,  though  it  may  look  less  satisfactory 
on  analysis,  is  more  practically  useful,  because  it  does  not 
absorb  water  nor  turn  rancid  on  storage.  Palm  kernel 


142  PLANT  PRODUCTS 

cake  has  a  very  dry  and  unsatisfactory  flavour.  Unless 
it  be  mixed  with  some  damp  food  the  cattle  will  merely 
blow  it  away  with  their  noses,  and  never  eat  it  at  all,  but  if 
it  be  moistened,  or  mixed  with  turnips,  the  cattle,  after  a 
little  experience,  can  be  induced  to  eat  it.  The  difficulty 
under  this  head  is  only  what  has  been  observed  on  many 
occasions  before,  cattle  do  not  take  readily  to  new-fashioned 
food,  and  it  takes  a  good  deal  of  patience  and  persuasion 
to  induce  them  to  eat  something  they  have  never  tasted 
before.  In  time,  of  course,  these  difficulties  are  overcome. 

Earth  Nuts. — The  earth  nut,  or  ground  nut,  is  a  tropical 
annual  leguminous  crop  which  has  the  peculiarity  that  the 
fruits  bury  themselves  in  the  earth.  It  will  grow  in  sandy 
soils,  is  very  valuable  as  a  course  in  tropical  rotations,  and 
lends  itself  well  in  conjunction  with  cotton  on  irrigated  light 
land.  In  some  cases  the  ripe  fruits  are  actually  dug  out  of 
the  earth,  or  in  others  the  crop  is  taken  before  the  fruits 
have  had  time  to  enter.  Earth  nuts  are  largely  grown  in 
Madras,  and  shipped  from  Pondicherry  to  Marseilles.  The 
best  qualities  come  from  Rufisque,  in  Senegal.  Sometimes 
the  pods  are  removed  from  the  beans,  and  sometimes  the 
materials  are  pressed  whole.  The  actual  bean  contains 
about  40  to  45  per  cent,  of  oil,  and  28  per  cent,  of  albuminoids. 
Earth  nuts  are  not  infrequently  fractionally  expressed,  the 
best  quality  oil,  cold  drawn,  being  expressed  at  the  ordinary 
temperature,  and  one  or  two  other  fractions  made  at 
increasing  temperatures  afterwards.  The  best  qualities 
of  oil,  that  is,  those  that  are  cold  drawn,  are  used  in  the 
manufacture  of  salad  oil,  and  the  second  qualities  for  the 
preservation  of  sardines,  and  the  manufacture  of  margarine. 
The  lowest  quality,  that  expressed  at  the  highest  temperature, 
is  used  for  soap -making.  A  characteristic  fatty  acid  of 
earth  nuts  is  arachidic  acid.  Earth-nut  oil  is  a  non-drying 
oil.  Earth-nut  oil  is  largely  used  to  replace  olive  oil  in  all 
its  uses.  When  the  husks  are  removed,  the  resulting  cake 
contains  7  to  9  per  cent,  of  oil,  and  45  to  48  per  cent,  of  albu- 
minoids, and  5  to  7  per  cent,  of  fibre.  When  the  husks 
have  not  been  removed,  the  fibre  may  vary  from  about 


THE  FORMATION  OF  OILS  IN  PLANTS    143 

1 8  to  30  per  cent.,  with  a  corresponding  reduction  in  the 
other  constituents.  The  resulting  cake  is  highly  esteemed 
as  a  cattle  food,  being  of  a  very  palatable  nature. 

Rape  Seed  (Colza,  Sarson). — Rape  seed  is  grown  in 
European  countries  and  also  very  largely  in  India.  The 
bulk  of  the  East  Indian  seed  is  imported  from  Calcutta, 
Madras,  and  Bombay,  the  large-growing  districts  being  in 
Guzerat  and  Ferozepore.  Rape  seed  contains  about  33 
to  43  per  cent,  of  oil,  22  to  27  per  cent,  albuminoids,  and  4 
per  cent,  fibre,  the  French  seed  being  the  richest  in  oil. 
It  is  crushed  between  rollers  in  the  same  way  as  the  other 
oil  seeds.  The  crude  oil  is  dark  coloured,  and  generally  needs 
to  be  refined  by  treating  at  the  ordinary  temperature  with 
about  i  per  cent,  strong  sulphuric  acid.  The  cold-drawn 
oil  is  used  in  India  as  an  edible  oil.  The  oil  is  also  used  for 
lubricating  purposes,  and  for  the  manufacture  of  soap. 
The  cakes  obtained  after  pressing  the  oil  are  of  somewhat 
doubtful  utility  for  feeding  cattle.  Rape  seed  often  contains 
materials  which  develop  a  mustard  oil  after  hydrolysis 
by  an  enzyme.  The  amount  of  proper  enzyme  in  rape  is 
commonly  deficient,  but  the  admixture  of  mustard  seed 
provides  the  necessary  enzyme  for  developing  the  mustard 
oil.  The  problem  is,  therefore,  parallel  to  the  development 
of  prussic  acid  in  linseed.  When  the  cakes  are  perfectly 
pure,  and  free  from  mustard  seed,  and  have  not  become 
acted  upon  by  heat  and  moisture,  the  material  may  be 
fed  with  safety,  but  there  is  always  the  risk  that  either 
insufficient  cleaning  in  manufacture,  or  improper  systems 
of  feeding  the  cattle,  may  give  rise  to  the  development  of 
mustard  oil,  which  is  pungent  and  irritating  to  the  animals, 
and  has  been  reported  to  have  actually  caused  death. 

Safflower  Seed. — This  plant  has  been  grown  in  India 
to  a  large  extent,  originally  for  the  preparation  of  saffron 
dye,  but  the  seeds  are  also  pressed  for  their  oil.  They  are 
rich  in  oil,  containing  30  to  35  per  cent.,  but,  owing  to  the 
very  thick,  springy  husk,  great  difficulty  occurs  in  expressing 
the  oil,  but  the  oil  is  prepared  in  India  on  a  small  scale  for 
local  purposes,  being  largely  used  for  human  consumption. 


144  PLANT  PRODUCTS 

On  the  small  scale,  it  is  not  infrequent  to  mix  the  safflower 
seed  with  other  seeds  before  pressing.  Safflower  oil  has  good 
drying  properties,  but  not  equal  to  linseed.  It,  nevertheless, 
can  replace  linseed  for  such  purposes  as  preserving  ropes, 
etc.,  from  the  action  of  water  and  air.  It  is  used  in  India 
also  largely  for  decorative  purposes,  the  "  wax  cloth  "  being 
largely  made  by  drawing  artistic  designs  with  the  aid  of  this 
oil,  and  then  dusting  on  mica,  or  other  glistening  materials. 
The  saffron  dye  is  made  from  the  yellow  florets,  which  are 
plucked  and  dried. 

Sesame,  Gingelly,  Til  Seed  (Sesamum  Indicum). — 
This  is  an  annual  plant  grown  throughout  the  tropics  and 
sub-tropics.  Sesame  seeds  are  lich  in  oil,  containing  from 
45  to  57  per  cent,  of  oil  and  usually  have  to  be  pressed  more 
than  once.  The  bulk  of  the  business  has  previously  been 
carried  out  at  Marseilles,  where  a  cold-pressed  oil  is  obtained 
first,  and  then  further  oils  obtained  by  the  addition  of  water 
and  the  raising  of  the  temperature,  by  which  means  another 
10  per  cent,  can  be  obtained.  The  best  quality  oil,  cold 
pressed,  is  a  good,  colourless  and  odourless  oil,  but  that 
obtained  from  the  later  pressings  is  of  inferior  quality. 
Sesame  oil  is  a  slow-drying  oil,  and  is  liable  to  become  rancid 
with  considerable  rapidity.  It  can,  however,  be  used  as  a 
substitute  for  olive  oil,  and  is  used  in  the  manufacture  of 
margarine,  the  lower  qualities  being  used  for  soap-making 
and  for  rather  inferior  lubricating  oils.  The  cake  contains 
about  30  to  40  per  cent,  of  albuminoids  and  only  6  per  cent, 
fibre. 

Niger  Seed  is  a  plant  originally  coming  from  Abyssinia, 
but  is  now  also  cultivated  in  India.  The  seeds  contain 
about  40  per  cent,  of  oil,  19  per  cent,  albuminoids,  and  14 
per  cent,  fibre,  whilst  the  cake  contains  30  to  35  per  cent, 
albuminoids  and  18  per  cent,  fibre. 

Mowha  or  Mowra  Seed  (Bassia  Seed). — The  two 
species  of  bassia  which  provide  the  mowha  seed  are  grown 
in  India  and  Ceylon,  one  species  grown  in  the  northern  or 
extra-peninsular  portion,  and  the  other  in  the  southern  or 
peninsular  portion.  Mowha  fat  is  soft  and  yellow,  like 


THE  FORMATION  OF  OILS  IN  PLANTS    145 

butter,  and  can  be  used  for  edible  purposes.  It  is  removed 
from  the  mowha  kernels  in  the  same  way  as  most  forms  of 
oil.  The  cake  left  after  crushing  the  oil  contains  much 
saponin,  a  poisonous  glucoside.  The  cake  has  been  fed  to 
cattle  without  actually  killing  them,  but  the  feeding  results 
have  been  very  unsatisfactory.  Efforts  have  been  made  to 
extract  the  saponin  by  a  commercial  method,  but,  up  to  the 
present,  no  particular  success  has  resulted.  Mowha  cake, 
as  well  as  the  true  soap  nut,  has  been  used  for  exterminating 
worms  from  lawns,  and  for  several  other  horticultural 
purposes.  As  the  mowha  cake  has  some  manurial  value, 
and  is  relatively  rather  rich  in  potash,  after  the  saponin  has 
done  its  work  of  destroying  insect  life,  it  serves  as  a  manure, 
the  nitrogen  amounting  to  2j  per  cent,  and  the  potash  to 
1 1  per  cent. 

Hemp  Seed  Oil. — Hemp  has  been  referred  to  for  its 
fibre  (see  p.  127),  but  the  seed  can  also  be  pressed  for  its 
oil.  When  fresh  drawn,  the  oil  is  of  a  pale  colour,  but  soon 
becomes  darker  on  keeping.  It  is  used  for  illuminating 
purposes,  for  soap,  and  also  in  varnishes. 

The  Essential  Oils.— The  greater  number  of  these  oils 
are  used  as  scents,  requiring  a  special  trade,  but  of  the 
common  materials  under  this  class,  oil  of  turpentine  is 
the  most  important.  Many  species  of  pine  trees  serve  as 
sources  for  this  material.  Under  the  best  systems,  after 
carefully  removing  the  bark,  vertical  incisions  are  made  in 
the  tree.  Sticky  resinous  matter  oozes  out,  and  is  received 
by  a  cup,  which  is  placed  immediately  under  the  slits.  These 
slits  are  gradually  extended  in  an  upward  direction,  and  the 
cups  follow  them.  When  the  crude  exudation  of  the  trees 
is  distilled  with  water,  oil  of  turpentine  distils  over,  and  the 
remaining  material  is  known  as  colophony  or  rosin. 

REFERENCES   TO   SECTION   III 

Souchida,  "  Notes  on  Some  Fatty  Oils,"  Journ.  Soc.  Chem.  Ind.t  1916, 
p.  1089. 

Imperial  Institute  Monograph,  "  Oil  Seeds  and  Feeding  Cakes." 
(Murray.) 

Leathes,  "  The  Fats.     Monograph  on  Bio-chemistry."     (Longmans.) 

D.  10 


146  PLANT  PRODUCTS 

Collins,  "The  Rate  of  Evolution  of  Hydrocyanic  Acid  from  Linseed 
under  Digestive  Conditions,"  Proc.  Univ.  Durham  Phil.  Soc.,  1912,  iv. 
P-  99  >  Journ.  Chem.  Soc.,  1912,  A.  ii.  586. 

Collins,  "  The  Feeding  of  Linseed  to  Calves,"  Journ.  Board  of  Agriculture, 
1915-16,  p.  120. 

"  Linseed  as  a  Farm  Crop,"  Journ.  Board  of  Agriculture,  1915-16, 
p.  1069. 

Morrell,  "  Polymerized  Drying  Oils,"  Journ.  Soc.  Ghent.  Ind.,  1915, 
p.  105. 

Hyland  and  Lloyd,  "  The  Oxidation  of  Fatty  Acids,  "Journ.  Soc.  Chem. 
Ind.,  1915,  p.  62. 

Maidment,  "  The  Home  Dairy,"  pp.  13  and  94.     (Simpkin,  Marshall.) 

Collins  and  Blair,  "  The  Liberation  of  Hydrocyanic  Acid  from  Linseed," 
Analyst,  1914,  p.  70. 

Fowler,  "  Bacterial  and  Enzyme  Chemistry,"  p.  160.     (Arnold.) 

Voelcker,  "  The  Characters  of  Pure  and  Mixed  Linseed  Cakes."  (Clowes.) 
Journ.  Roy.  Agric.  Soc. 

Vakil,  "  Cotton  Seed  Products,"  Journ.  Soc.  Chem.  Ind.,  1917,  p.  685. 

Crowther,  "  Palm  Kernel  Cake,"  Journ.  Board  of  Agriculture,  1916-17, 

P-  734- 

Crowther,  "  Palm  Kernel  Cake  and  Meal  as  Food  for  Pigs,"  Journ. 
Board  of  Agriculture,  1916-17,  p.  850. 

Browning  and  Symons,  "  Cocoanut  Toddy  in  Ceylon,"  Journ.  Soc. 
Chem.  Ind.,  1916,  p.  1138. 

"Ground  Nut  Cake,"  Journ.  Board  of  Agriculture,  1915-16,  p.  308. 

Collins,  "  Agricultural  Chemistry,"  p.  14.  (Government  Printing 
Office,  Calcutta.) 

Roure  Bertrand  Fils,  Bulletins.     (Grasse,  France.) 

Copeland,  "  The  Coconut."     (Macmillan.) 

Dunstan  and  Henry,  "  Cyanogenesis  in  Plants,"  Proc.  Roy.  Soc.,  1903, 
p.  285. 

Auld,  "  The  Hydrolysis  of  Amygdalin,"  Journ.  Chem.  Soc.,  1908, 
T.  1251. 

Bulletin  Imperial  Institute,  "Palm  Kernels,"  1914,  p.  459. 

"  The  Cultivation  of  Soy  Beans  in  Britain,"  Journ.  Board  of  Agri- 
culture, 1912-1913,  p.  33.. 

"  The  Growing  of  Linseed  for  Feeding  Purposes,"  Journ.  Board  of 
Agriculture,  1913-14,  p.  377. 

Eyre  and  Fisher,  "  Some  Considerations  affecting  the  Growing  of 
Linseed  as  a  Farm  Crop  in  England,"  Journ.  Agric.  Science,  vii.,  p.  120. 

Mitchell,  "Edible  Oils  and  Fats,"  p.  24.     (Longmans.) 

Parry,  "Gums  and  Resins."     (Pitman.) 


SECTION  IV.— THE  NITROGEN  COMPOUNDS 
IN  PLANTS 

As  the  study  of  the  animal  proteins  already  forms  the 
chief  subject  matter  of  one  of  the  other  books  of  this  series 
(Bennett),  it  will  only  be  necessary  to  indicate  in  this  section 
some  of  the  differences  occurring  between  the  vegetable 
proteins  and  the  animal  proteins,  and  to  give  details  of 
nitrogenous  bodies  other  than  proteins. 

The  Cereal  Proteins. — In  the  eighteenth  century  a 
considerable  amount  of  work  was  done  in  examining  the 
protein  matter  in  wheat.  In  1747  Beccari  examined  wheat 
flour,  and  concluded  that  wheat  gluten  resembled  animal 
matter.  The  process  chiefly  used  in  that  day  was  destructive 
distillation.  Kessel  Myer,  in  1759,  determined  the  action 
of  various  sulphates  upon  wheat  gluten,  and  in  1773  Rouelle 
showed  that  the  wheat  gluten  was  also  present  in  various 
other  plants.  Parmentier  showed  that  wheat  gluten  was 
insoluble  in  mineral  acids,  but  soluble  in  vinegar,  and  that 
there  was  some  relationship  between  ther^colour  of  flour  and 
its  gluten  content.  In  the  nineteenth  century  the  solubility 
of  wheat  gluten  in  alcohol  was  also  considered,  and  the 
elementary  position  of  the  proteins  began  to  be  accurately 
studied.  Destructive  distillation  at  this  period  seems  to  have 
been  the  method  of  the  investigators. 

The  chief  protein  in  wheat  grain  is  now  called  glutenin, 
and  the  next  most  important  gliadin.  These  are  contained 
in  slightly  greater  quantities  in  spring  wheat  than  in  winter 
wheat,  but  this  variation  is  very  likely  due  to  the  longer 
period  during  which  winter  wheat  grows.  Reserve  seed 
proteins  are  usually  more  stable  towards  reagents  than  the 
proteins  which  form  part  of  the  living  substances  of  the 


148  PLANT  PRODUCTS 

plant,  and  the  composition  of  the  reserve  proteins  appears 
to  vary  more  than  does  the  composition  of  the  proteins  that 
take  part  in  the  active  life  of  the  plant.     Extraction  with 
somewhat  diluted  alcohol  has  been  employed  to  remove  some 
of  the  proteins  of  cereal  seeds,  although  in  other  seeds  such 
extraction  with  alcohol  yields  but  little  protein.     Extraction 
with  alcohol  can  be  made  at  any  temperature  up  to  its  boiling 
point,  if  the  alcohol  is  sufficiently  concentrated  to  inhibit 
hydrolysis.     By  evaporating  such  a  solution  in  fairly  strong 
alcohol,  the  alcohol  evaporates  first,  the  percentage  of  water 
increases,  and  the  proteins  become  insoluble.     On  the  other 
hand,  from  fairly  concentrated  solutions  protein  may  also 
be  separated  by  adding  absolute  alcohol,  since  in  absolute 
alcohol    proteins    are    insoluble.      The    addition    of    ether 
assists  in  this  precipitation  of  protein.     Roughly  speaking, 
solutions    containing    less   than   50   per  cent,    of   alcohol, 
or  more  than  93  per  cent,  of  alcohol,  do  not  dissolve  cereal 
proteins.     Other  alcohols  than  ethyl  alcohol  can  be  used  for 
solutions.     Zein,  from  maize,  can  be  dissolved  in  boiling 
acetic  acid  without  any  apparent  change,  and  is  also  particu- 
larly resistant  to  the  action  of  alkalies,  even  2  per  cent, 
of  potassium  hydrate  at  40°  Cent,  during  24  hours  giving 
little   evidence   of   alteration.     Zein  also   shows   a   unique 
behaviour  towards  alcohol,  because,  when  dissolved  in  strong 
alcohol,  the  solution  becomes  gelatinated.     In  such  circum- 
stances, however,  the  original  nature  of  the  protein  appears 
to  be  permanently  altered.     The  globulins  differ  in  a  marked 
degree  from  the  animal  proteins,  for  most  of  them  are  very 
incompletely  coagulated  by  heating  the  solution,  even  to 
boiling  point.     The  vegetable  proteins  have  a  fairly  marked 
specific    rotary    power    towards    polarized    light.     Gliadin, 
from  wheat,   rye,  and  barley,   has   a  high  rotary  power, 
corresponding  to  about  —  100° ;  but  zein,  from  maize,  has 
a   relatively    low    specific    rotary  power   of    about   —  30°. 
The  hydrolysis  by  acids  of  the  vegetable  proteins  are  of 
much  the  same  general  character  as  those  from  the  animal 
proteins.     The  vegetable  proteins  are  generally  more  difficult 
to  completely  hydrolize  than  the  animal  proteins,  and  a 


THE  NITROGEN  COMPOUNDS   IN  PLANTS    149 

much  longer  hydrolysis  is  generally  found  necessary.  The 
amino  acids  which  have  been  obtained  from  the  vegetable 
proteins  are  the  same  as  those  yielded  by  the  animal  proteins 
with  the  exception  of  di-amino-trioxy-dodecanic  acid.  In 
general,  the  plant  proteins  yield  more  glutaminic  acid  and 
ammonia  than  do  the  animal  proteins.  The  proteins  soluble 
in  alcohol  yield  the  basic  amino  acids  in  a  very  small  pro 
portion,  and  yield  no  lysine.  The  vegetable  proteins  always 
contain  more  nitrogen  than  the  animal  proteins.  The  split- 
ting products  of  the  cereal  proteins  are  marked  by  the  high 
proportion  of  non-basic  nitrogen,  the  low  proportion  of 
basic  nitrogen,  the  high  proportion  of  ammoniacal  nitrogen, 
and  the  small  amount  of  lysine.  Glutenin  and  gliadin, 
both  wheat  products,  are  characterized  by  the  high  yield 
of  ammonia  in  comparison  with  the  glutaminic  and  aspartic 
acids  present.  These  proteins  must,  therefore,  contain  some 
nitrogen  not  occurring  in  the  usual  type  of  amino-acid  amide 
like  asparagine.  A  marked  division  between  the  cereal 
proteins  and  those  of  animal  origin  lies  in  the  fact  that  the 
former  are  completely  free  from  phosphorus.  Of  course, 
imperfectly  purified  specimens  will  contain  some  phosphorus 
adhering  to  them.  A  very  important  correlation  is  brought 
out  when  the  character  of  the  proteins  in  the  seeds  is  compared 
with  the  ordinary  botanical  relationship  of  the  natural 
orders  concerned.  The  proteins  contained  in  the  seeds  of 
the  cereals  contain  a  relatively  large  proportion  of  those 
protamins  which  yield  no  lysine,  muc^.  proline,  glutaminic 
acid,  and  ammonia,  with  a  little  arginine  and  histidine. 
Hordein,  in  barley,  is  characterized  by  its  low  percentage  of 
oxygen  and  large  heat  of  combustion. 

The  chief  properties  and  behaviour  of  the  cereal  proteins 
are  much  alike,  and  present  marked  differences  from  the 
proteins  from  other  groups  of  seeds.  It  is  thus  found  that 
similar  proteins  are  found  only  in  seeds  which  are  botanically 
closely  related.  The  embryo  in  its  early  periods  of  growth 
is  fed  on  special  food,  but  when  the  plant  has  reached  the 
stage  of  finding  food  from  its  surroundings,  the  chemical 
processes  have  already  become  established  on  fixed  lines. 


150  PLANT  PRODUCTS 

Wheat  grown  on  irrigated  land  contains  less  nitrogen 
than  that  grown  on  non-irrigated  land,  but  this  may  quite 
possibly  be  only  part  of  the  general  principle  that  vigorous 
growth  results  in  the  production  of  carbohydrates. 

Crude  gluten  from  wheat  amounts  to  8  to  15  per  cent,  of 
the  wheat  flour,  No.  i  Manitoba  wheat  flour  containing  over 
13  per  cent,  and  English  flours  under  10  per  cent. 

Crude  gluten  dried  at  a  low  temperature  is  used  to  make 
biscuits  for  diabetes  patients. 

Leguminous  Proteins. — Many  of  the  leguminous  seeds, 
such  as  peas,  beans,  and  lentils,  contain  relatively  much 
protein  soluble  in  water,  which,  after  the  addition  of  acetic 
and  carbonic  acids,  is  largely  precipitated,  but  is  soluble 
again  in  concentrated  saline  solutions,  and  is  generally 
considered  as  a  globulin.  It  was  formerly  supposed  that 
many  proteins  were  strong  acids  in  all  but  name,  and  formed 
salts  with  bases,  on  which  grounds  many  of  the  proteins 
were  described  in  older  literature  as  caseins.  The  legumin 
from  peas  and  beans  was  long  regarded  as  a  protein  of  strong 
acid  character.  Recent  studies  have,  however,  shown  that 
the  solubility  caused  by  the  addition  of  large  quantities 
of  alkali  is  not  due  to  this.  lyegumin  in  the  free  state  is 
soluble  with  water,  but  when  combined  with  acids  forms 
salts  which  are  insoluble,  and  the  idea  that  legumin  is  a  strong 
acid  in  a  free  state,  but  forming  salts,  is  no  longer  a  tenable 
hypothesis.  Many  of  the  leguminous  seeds,  when  freshly 
ground,  yield  water  extract,  from  which  the  protein  separates 
by  the  development  of  acid.  The  separation  can  quickly 
be  effected  by  adding  a  small  quantity  of  any  common  acid. 
L,egumin,  previously  dissolved  in  dilute  sodium  hydrate, 
is  not  precipitated  by  adding  enough  acid  to  combine  with 
all  the  alkali  that  has  been  added,  but  very  little  more  acid 
forms  an  insoluble  salt  of  legumin.  Still  further  addition 
of  acid,  however,  suffices  to  redissolve  the  precipitate. 
The  leguminous  proteins  are  usually  particularly  rich  in 
nitrogen,  and  yield  on  hydrolysis  a  large  proportion  of 
arginine. 

Vicilin,  from  peas,  is  characterized  by  the  small  amount 


THE  NITROGEN  COMPOUNDS   IN  PLANTS     151 

of  ammonia  in  proportion  to  the  amount  of  glutaminic 
and  aspartic  acids,  and  must,  therefore,  contain  those 
amino  acids  in  a  form  different  from  that  of  the  amide. 
This  protein  has  also  been  found  to  contain  very  little  sulphur. 
The  proteins  from  leguminous  seeds  resemble  one  another 
in  many  respects,  but  differ  from  those  of  the  cereals.  The 
proteins  of  the  pea,  horse  bean,  lentil,  and  vetch  all  yield 
preparations  of  legumin  which  are  apparently  identical. 
Other  members  of  the  leguminous  series  yield  proteins  which 
are  very  similar  to  those  yielding  legumin,  and  though  not 
identical,  are  much  nearer  to  legumin  than  any  of  the 
proteins  found  in  the  cereals.  The  legumin  of  soy  bean  is 
used  in  Japan  to  make  a  vegetable  cheese.  The  soy  beans 
are  treated  as  in  the  manufacture  of  starch  (see  p.  117), 
but  the  non-starch  residue  is  kept,  boiled,  strained,  and 
precipitated  with  brine.  The  cheese  resembles  a  half  milk 
cheese. 

The  Proteins  in  Root  Crops. — Early  investigators 
examined  the  proteins  of  the  potato,  but  no  great  amount 
of  work  has  been  done  in  this  group.  The  hydrolysis  of 
the  protein  of  the  swede  turnip  produces  substances  which 
differ  from  those  yielded  by  the  legumins  chiefly  in  the 
following  points  : — The  percentage  <of  arginine  resembles 
that  yielded  by  the  ceieals,  and  is  distinctly  less  than  that 
from  the  leguminous  crops.  The  percentage  of  histidine 
is  rather  high.  The  percentage  of  lysine  is  faitly  high,  and 
corresponds  to  that  from  the  legumes.  The  low  content  of 
glutaminic  acid  in  the  soluble  protein  of  swedes  will  counter- 
balance the  high  content  of  that  amino  acid  in  the  proteins 
of  cereals  when  these  two  are  fed  together,  as  is  common  in 
ordinary  farm  practice.  Both  cystine  and  tryptophane  are 
also  present  in  the  swede  protein. 

The  Proteins  of  the  Oil  Seeds.— The  globulin  in 
castor  bean  can  be  freed  by  dialysis  from  all  but  minute  traces 
of  the  toxic  substances  contained  in  the  beans,  a  fact  which 
forms  one  of  the  best  pieces  of  evidence  that  these  materials 
can  be  obtained  in  at  least  some  degree  of  purity.  Edestin, 
the  chief  protein  of  hemp  seed,  is  entirely  insoluble  in  water, 


152  PLANT  PRODUCTS 

but  is  very  readily  soluble  in  small  traces  of  acid,  in  the 
absence  of  other  salts.  From  such  a  solution  the  edestin  is 
readily  precipitated  by  sodium  chloride.  Edestin,  in  fact, 
has  proved  to  be  a  fairly  strong  base,  and  the  combined  acid 
in  its  salts  can  be  titrated  by  potash  and  phenol-phthalein. 

The  maximum  acid  binding  power  of  edestin  is  very 
high  indeed.  The  solubility  of  edestin  in  salt  solutions  is 
approximately  the  same,  but  the  iodides  and  bromides  dis- 
solve edestin  more  readily  than  the  chlorides.  Acetates 
behave  in  a  somewhat  remarkable  manner,  for  the  acetates 
of  the  alkalies  have  no  solvent  action  on  edestin,  while  the 
acetates  of  heavy  metals  dissolve  it  freely.  The  acetates 
of  lead,  copper,  and  silver,  which  are  commonly  supposed 
to  be  protein  precipitants,  are  as  good  solvents  for  edestin 
as  is  pure  acetic  acid,  provided  other  salts  be  absent.  The 
metallic  ion  of  the  acetate  unites  in  organic  combination 
with  the  protein.  Corylin,  from  hazel  nuts,  is  characterized 
by  containing  the  very  high  amount  of  19  per  cent,  of  nitrogen, 
of  which  nearly  one-third  is  basic  nitrogen.  The  proteins 
in  this  group  are,  on  the  whole,  characterized  by  high 
percentages  of  nitrogen,  with  moderate  amounts  of  ammonia, 
and  very  high  amounts  of  basic  nitrogen,  with  large  quantities 
of  arginine  and  moderate  amounts  of  histidine.  The  castor 
bean  contains  toxic  substances,  which  appear  to  be  of 
protein  character,  although  this  is  not  accepted  by  all 
workers,  but  preparations  have  been  made  of  ricin,  of  which 
2000  Part  °f  a  milligram  per  kilogram  weight  was  a  fatal 
dose  when  subcutaneously  injected  into  rabbits,  and  such 
rich  preparations  contain  a  high  percentage  of  albumen. 

The  Alkaloids. — Opium  is  the  dried  milky  juice  (latex) 
of  the  unripe  capsules  of  the  poppy.  The  opium  poppy  is 
cultivated  in  India  and  China  from  seed,  which  is  sown  from 
November  to  March,  and  the  crops  are  ready  from  May  to 
July.  A  few  days  after  the  petals  have  fallen  the  capsules 
are  cut  round  the  middle  with  a  knife,  and  on  the  following 
morning  the  juice  has  flowed  out,  hardened,  and  is  ready  for 
collection.  After  further  drying  on  poppy  leaves,  the  dark 
masses  are  made  up  into  lumps.  Opium  is  used  medicinally, 


THE  NITROGEN  COMPOUNDS   IN  PLANTS    153 

and  also  is  smoked,  chiefly  by  the  Chinese.  Opium  contains 
many  alkaloids — morphine  about  9  per  cent.,  narcotine  about 
5  per  cent.,  and  other  alkaloids  about  i  per  cent.  Morphine 
exists  in  opium  in  the  form  of  two  soluble  salts,  so  that 
extraction  with  water  removes  all  this  alkaloid.  Gregory's 
method  for  the  manufacture  of  morphia  consists  in  extracting 
the  drug  with  water  at  about  40°  Cent.,  mixing  the  liquor 
with  excess  of  calcium  carbonate,  and  evaporating  to  a  small 
volume.  Calcium  chloride  is  added  to  a  slight  excess,  the 
liquid  diluted,  and  a  precipitate,  consisting  of  resin  and 
calcium  meconate,  filtered  off.  On  concentrating  the  liquid 
the  hydrochloride  of  morphine  crystallizes  out.  This 
is  dissolved  in  water,  the  solution  decolorized  with  charcoal, 
and  decomposed  by  ammonia,  which  precipitates  the  morphia 
nearly  pure.  Further  purification  is  effected  by  ether  and 
benzene. 

Cinchona  (Peruvian  Bark). — The  tree  which  yields  this 
bark  is  a  native  of  Peru,  and  the  value  of  the  bark  for  curing 
intermittent  fevers  was  known  to  the  American  natives 
before  the  conquest  of  Peru,  but  they  concealed  its  value 
for  a  long  time.  In  1638,  however,  the  Countess  Cinchon 
obtained  the  use  of  this  for  the  cure  of  ^ever,  and  subsequently 
brought  quantities  of  ground  bark  to  Europe,  where  it  was 
known  by  the  name  of  the  "  Powder  of  the  Countess." 
Subsequently  it  became  known  to  the  Jesuits,  and  was 
usually  called  "  Jesuit's  Bark."  Three  kinds  of  bark  are 
commonly  known,  the  pale  bark,  the  yellow  bark,  and  the 
red  bark.  The  cinchona  trees  are  now  cultivated  in  many 
parts  of  the  world,  considerable  quantities  being  grown  and 
manufactured  in  India  under  Government  supervision. 
The  use  of  plain  bark  is  no  longer  very  large  in  medical 
practice,  being  replaced  by  the  purer  drugs.  The  total 
alkaloids  of  Peruvian  bark  are  first  extracted  with  water, 
and  dissolved  for  the  most  part.  The  cincho-tannates  may 
be  dissolved  by  a  dilute  acid,  or  they  may  be  decomposed 
by  mixing  the  bark  with  lime  and  water.  Extraction 
with  dilute  hydrochloric  acid  is  not  usually  employed  now. 
On  the  large  scale,  finely  powdered  bark  is  mixed  with  lime, 


154  PLANT  PRODUCTS 

and  made  into  a  paste  with  water.  The  mixture  is  thoroughly 
dried,  powdered,  and  extracted  with  chloroform,  ether,  etc. 
The  alkaloids  are  removed  from  the  solvent  by  agitating 
it  with  dilute  acid,  and  then  precipitated  by  ammonia. 
The  alkaloids  thus  obtained  are  chiefly  composed  of  quinine, 
hydroquinine,  cinchonine,  cinchonidine,  and  a  little  quinidine. 
Crude  alkaloids  of  this  nature  are  not  infrequently  employed 
as  medicine,  especially  in  India,  where  they  may  be  sold 
under  such  titles  as  cinchona  febrifuge,  sometimes  misnamed 
by  the  natives  as  cinquinine.  A  nearly  complete  separation 
of  the  quinine  may  be  effected  by  taking  advantage  of  the 
small  solubility  of  quinine  in  cold  water.  Quinine  is  a 
fairly  strong  base,  giving  two  sets  of  salts,  mono-acid  and 
di-acid. 

Nicotine. — Nicotine  is  prepared  chiefly  from  the  tobacco 
leaf,  mid-ribs,  and  waste  tobacco,  and  from  the  liquors  which 
are  by-products  of  tobacco  intended  for  chewing  purposes. 
These  materials  are  extracted  with  water,  and  the  liquor 
concentrated.  After  the  addition,  steam  distillation  gives  a 
liquor  containing  a  crude  form  of  nicotine.  This  is  acidified 
with  oxalic  acid,  and  evaporated  to  a  small  bulk,  subsequently 
decomposed  by  potash,  and  the  nicotine  floats  on  the  surface, 
and  is  separated  mechanically.  Waste  tobacco  and  crude 
forms  of  nicotine  are  largely  used  as  insecticides,  especially 
for  horticultural  work. 

Tobacco. — Tobacco  can  be  grown  in  the  British  Isles 
where  the  cool  moist  temperature  on  the  west  coast  makes  the 
tobacco  plant  fairly  independent  of  variations  of  soil  moisture, 
which  is  such  an  important  point  in  all  tobacco-growing 
districts,  and  perhaps  accounts  for  the  fact  that  on  the  west 
coast  of  the  British  Isles  small  degrees  of  frost  are  not  found 
to  be  fatal,  whilst  on  the  European  continent  a  frost  is  con- 
sidered a  fatal  difficulty.  Any  good  soils  can  be  made 
suitable  by  tillage  for  the  production  of  tobacco,  but  the 
plant  flourishes  best  in  a  fairly  open  soil,  which  is  well 
supplied  with  organic  matter. 

Tobacco  is  especially  sensitive  to  the  amount  of  lime  in 
the  soil.  Continental  practice  considers  that  the  amount 


THE  NITROGEN  COMPOUNDS  IN  PLANTS     155 

of  lime  in  the  soil  should  not  be  less  than  J  per  cent.,  and  not 
more  than  2  per  cent. 

The  manures  used  contain  a  high  percentage  of  potash, 
but  no  large  amount  of  phosphates.  The  fields  on  which 
tobacco  is  planted  out  must  be  well  sheltered  from  wind. 
Tobacco  may  be  substituted  for  potatoes  or  other  crops  in 
the  rotation  or  can  be  grown  several  years  successively. 
On  the  continent  phosphates  are  not  usually  applied  direct 
to  the  tobacco,  the  previous  crop  in  the  rotation  having 
already  received  heavy  dressings  of  phosphates  in  advance. 
Chlorides  are  considered  bad  for  the  development  of  the  plant. 
Compound  manures  containing  about  5  per  cent,  nitrogen, 
17  per  cent,  soluble  phosphate,  and  7  per  cent,  potash  are 
considered  very  suitable  for  this  crop,  which  corresponds 
roughly  to  about  one  part  of  sulphate  of  potash,  two  parts 
of  sulphate  of  ammonia,  and  four  parts  of  super-phosphate. 
Kainit  should  not  be  used  since  it  contains  too  much  chlorine. 
The  plant  is  usually  grown  on  low,  flat  drills,  very  frequently 
being  planted  out  in  the  furrow,  and  subsequently  earthed 
up.  The  seed  is  generally  sown  about  the  middle  of  March 
or  April  in  hot  beds.  The  suckers  and  lateral  growth  should 
be  broken  off,  and  the  plant  allowed  to  bear  ten  leaves. 
The  better  qualities  are  not  harvested  all  at  once,  but  plucked 
leaf  by  leaf.  They  are  then  dried,  and  taken  to  curing 
barns,  in  which  ventilation  is  an  important  point.  The  first 
process  consists  in  wilting  the  leaves,  when  they  lose  moisture, 
and  become  limp,  but  the  drying  should  not  take  place  too 
fast.  The  second  process  is  that  of  yellowing  the  leaf. 
This  subsequently  turns  to  brown,  and  the  leaf  becomes 
fairly  well  dried.  Then  drying  must  proceed  fairly  rapidly, 
in  order  to  prevent  mould  setting  in.  About  one  half  of 
a  ton  of  dry  tobacco  per  acre  represents  the  ordinary 
yield. 

In  tropical  climates  a  rich,  sandy  loam  is  preferred, 
containing  considerable  quantities  of  potash  and  lime. 
In  India  a  great  many  of  the  most  suitable  districts  contain 
well  waters  with  nitrates  in  solution,  which  are  used  for 
irrigating  purposes.  The  land  is  usually  thoroughly  ploughed 


156  PLANT  PRODUCTS 

and  thrown  up  into  riggs  and  furrows.  The  seeds  are  sown 
in  nurseries  in  a  shady  situation,  and  in  very  hot  districts 
it  is  necessary  to  protect  the  seedlings  from  excessive  heat 
at  this  stage.  Some  form  of  partial  sterilization  of  the  soil 
is  often  adopted  by  burning  the  soil,  along  with  weeds, 
brushwood  or  other  waste.  The  seedlings  are  generally 
transplanted  into  furrows,  where  they  may  possibly  be 
irrigated,  and  the  position  of  rigg  and  furrow  subsequently 
reversed  in  the  process  of  earthing  up.  Growth  has  usually 
proceeded  fairly  far  in  thirty  or  forty  days,  when  side  shoots 
and  small  buds  are  cut  off.  In  the  fields  twigs  and  sticks 
are  arranged  somewhat  like  a  towel-horse,  and  the  leaves 
arranged  on  these  for  drying  purposes.  In  some  cases  the 
leaves  are  fixed  to  strings,  very  much  like  a  washerwoman 
might  hang  out  stockings  to  dry.  Rapid  drying  produces 
a  pale  leaf,  but  slow  drying  produces  a  dark-coloured  leaf. 
The  process  of  maturing  does  not  consist  in  merely  losing 
water,  but  the  action  of  oxidizing  enzymes  is  an  important 
part  of  the  process.  The  starch  and  sugar  almost  entirely 
disappear,  and  the  albuminoids  and  the  tannin  decrease, 
with  an  increase  in  the  amounts  of  amides.  These  changes 
are  all  explained  by  ordinary  oxidizing  decomposition. 

Caffeine  or  Theine.— This  is  the  alkaloid  of  tea  and  coffee 
(see  Section  V.,  pp.  158, 160).  Coffee  beans  contain  about  i 
per  cent.,  and  tea  leaves  from  about  i  to  5  per  cent. ;  3^ 
per  cent,  is  considered  an  ordinary  amount  of  caffeine 
in  tea  leaves.  Tea  is  heated  for  about  an  hour  with  three 
or  four  times  its  weight  of  boiling  water,  and  after  filtration 
is  mixed  with  a  quantity  of  lime  equal  to  that  of  the  tea 
originally  taken.  The  mixture  is  subsequently  dried  on  the 
water-bath,  extracted  with  boiling  chloroform,  and  the 
solution  subsequently  recrystallized  by  alcohol.  Theobro- 
mine,  the  alkaloid  in  cocoa,  is  closely  related  to  caffeine. 

Strychnine  is  the  chief  alkaloid  in  Nux  Vomica.  The 
finely  powdered  seeds  are  treated  with  lime  and  water,  and 
the  mixture  extracted  with  chloroform,  benzene,  or  amyl 
alcohol. 


THE  NITROGEN   COMPOUNDS   IN  PLANTS     157 


REFERENCES   TO   SECTION    IV 

Shutt,  "  Influence  of  Environment  on  the  Composition  of  Wheat," 
Journ.  Soc.  Chem.  Ind.,  1909,  p.  336. 

Osborne,  "  The  Vegetable  Proteins."     (Longmans.) 

Plimmer,  "  The  Chemical  Constitution  of  the  Proteins,"  p.  76.  (Long- 
mans.) 

Wood  and  Hardy,  Proc.  Roy.  Soc.,  1909,  B.  81,  38. 

Hardy,  Brit.  Assoc.  Report,  1909,  p.  784. 

Gwilym  Williams,  "  Hydrolysis  of  the  Soluble  Protein  of  Swede 
Turnips,"  Journ.  Agric.  Science,  viii.,  p.  182. 

Thomas  Thomson,  "  Chemistry  of  Vegetables,"  p.  799.     (Bailliere.) 

Wallace,  "  Indian  Agriculture,"  p.  235.     (Oliver  and  Boyd.) 

Thorpe,  "  Dictionary  of  Applied  Chemistry,"  v.  627.  (Longmans, 
Green.) 

Garrad,  "  Tobacco  Growing  for  Insecticidal  Purposes,"  Journ.  Board 
of  Agriculture,  1911-12,  p.  378. 

"  Cultivation  of  Tobacco  for  the  Preparation  of  Fruit  and  Hop 
Washes,"  Journ.  Board  of  Agriculture,  1912-13,  p.  985. 

Whatnough,  "The  Cultivation  and  Collection  of  Medicinal  Plants  in 
England,"  Journ.  Board  of  Agriculture,  1914-15,  p.  492. 


SECTION  V. —MISCELLANEOUS  PLANT 
PRODUCTS 

Tea. — Tea  was  first  introduced  into  Europe  by  the  Dutch 
East  India  Company.  At  first  it  was  mostly  of  Chinese 
production,  but  of  recent  years  India  has  taken  the  major 
part  of  the  trade.  Tea  thrives  best  in  the  hilly  tracts,  and 
is  not  usually  grown  in  any  low-lying  districts,  or  at  any 
pronounced  altitude.  It  is  raised  from  seed,  and  the  bushes 
in  the  tea  plantation  are  kept  about  four  or  five  feet  apart, 
so  as  to  permit  ample  room  for  the  workers  to  get  in  between 
for  hoeing  operations.  The  aim  of  the  planter  is  to  obtain 
a  constant  succession  of  leaf -bearing  shoots,  but  the  plant 
requires  a  period  of  rest.  At  the  time  of  the  "  flush/'  or 
period  of  most  active  vegetation,  the  youngest  leaves  of  each 
shoot  are  alone  used  in  the  manufacture.  The  bushes 
must  on  no  account  be  allowed  to  produce  flowers  or  fruit. 
The  rainfall  in  tea-growing  districts  is  invariably  high,  about 
eighty  inches  per  annum  representing  a  fairly  satisfactory 
figure;  long  droughts  are  very  disadvantageous.  The  soil 
must  be  well  drained,  but  situations  on  the  sides  of  hills 
are  not  considered  very  satisfactory.  I4ght,  sandy,  loose, 
deep  loams  are  the  best  type  of  soil,  clays  and  shallow  soils 
being  quite  unsuited.  Nitrogenous  manures  are  extremely 
valuable,  and  moderate  amounts  of  vegetable  manure 
desirable,  but  excessive  vegetable  matter  leads  to  inferior 
grades.  In  Japan  fish  manure  is  used.  lyime  is  generally 
considered  to  be  very  harmful  except  in  small  amounts, 
though  in  Assam  lime  is  regarded  more  favourably.  In 
Dehra  Dun  gypsum  is  used.  There  seems  some  reason  to 
believe  that  tea  needs  an  abnormal  value  of  the  ratio  MgO  : 
CaO  in  the  soil,  and  requires  the  magnesia  to  be  in  marked 


TEA  159 

excess.  The  amount  of  phosphoric  acid  and  potash  appears 
to  have  an  important  influence  on  the  flavour.  The  seed 
is  sown  in  nurseries,  and  the  plants  are  ready  for  transplanting 
about  May.  Under  old  systems  of  planting  the  bushes  were 
arranged  almost  entirely  on  the  square,  but  it  is  becoming 
more  popular  now  to  plant  them  on  the  triangular  system. 
By  this  arrangement  a  greater  number  of  plants  can  be  put 
on  an  acre  with  the  same  distance  from  bush  to  bush. 
Incessant  hoeing  is  one  of  the  most  important  parts  of  the 
cultivation.  Farmyard  manure  is  not  obtainable  and  bullock 
dung  is  scarce  and  needed  for  food  production,  but  some 
form  of  green  manure  is  often  used  to  take  its  place. 
Unpalatable  oil  cakes  are  also  freely  used,  but  there  is  great 
difficulty  in  obtaining  sufficient  suitable  supplies  of  organic 
nitrogen  materials,  and  sulphate  of  ammonia  is  used  to  make 
up  for  this  deficiency.  The  tea  bush  will  often  last  out  from 
forty  to  sixty  years,  depending  upon  the  amount  of  pruning. 
Frequent  light  prunings  are  practised  and  heavy  prunings 
at  intervals  of  every  few  years.  The  pluckings  are  made 
by  pressure,  and  not  by  pulling,  andTthe  number  of  leaves 
taken  off  at  a  time  will  determine  the  quality  of  the  tea  ; 
the  better  qualities  having  about  three  leaves,  and  the  lower 
qualities  about  five  leaves.  The  period  of  plucking  is  most 
active  during  July,  August,  and  September,  when  the  result 
of  the  rains  produces  its  maximum  moisture  in  the  soil.  The 
tea  leaves  are  transferred  as  quickly  as  possible  to  a  withering 
house,  where  they  are  spread  out  in  trays.  This  place  must 
be  kept  as  cool  as  possible,  and  with  the  greatest  possible 
amount  of  ventilation,  to  allow  rapid  evaporation  of  water. 
When  the  leaf  has  become  sufficiently  flaccid  it  is  carried  to 
a  rolling  machine,  which  imitates  rolling  between  the  palms 
of  the  hands  as  in  the  original  primitive  Chinese  system. 
This  operation  breaks  up  the  cells  of  the  leaf,  and  allows  the 
different  parts  of  the  plant  juice  to  come  into  contact  with 
one  another,  so  that  much  of  the  chemical  change  which 
takes  place  is  due  to  the  enzymes  which  occur  in  the  tea 
itself,  and  as  little  as  possible  due  to  bacterial  decomposition. 
The  tea  is  then  transferred  to  the  sirocco,  or  drying  machine, 


160  PLANT  PRODUCTS 

which  usually  consists  of  a  long  boiler-shaped  vessel,  heated 
by  flues,  with  trays  which  are  transferred  from  one  end 
to  the  other  to  allow  drying  to  take  place  in  a  steady  manner. 
Once  the  tea  has  been  thoroughly  dried  it  is  necessary  that 
it  should  on  no  account  come  into  contact  with  moist  air. 
It  is  sieved  into  different  grades  as  quickly  as  possible,  and 
packed  into  lead-lined  boxes.  Many  qualities  of  tea  are 
very  sensitive  to  damp  atmosphere,  so  that  some  qualities 
which  are  known  in  the  immediate  vicinities  of  the  tea- 
producing  districts  are  quite  unknown  overseas,  as,  in  spite 
of  all  efforts  to  obtain  an  air-tight  tea  chest,  these  teas 
deteriorate  on  the  sea  passage.  Anything  approaching  to 
free  admission  of  sea  air  is  immediately  fatal  to  most  teas. 
No  matter  what  varieties  of  tea  are  taken  on  board  a  ship  in 
loosely  closed  vessels,  within  a  day  or  two  of  leaving  port 
they  all  seem  to  have  sunk  to  the  same  low  level  of  flavour. 
The  greatest  possible  care  is  taken  at  the  tea-packing  stations 
to  discover  even  pinpricks  in  the  lead  casings.  Many  of 
the  very  finest  qualities  of  tea  manufacture  in  China  and 
Japan  are  still  made  by  the  old  hand-rolling  process,  but 
modern  Indian  methods  are  becoming  very  common. 
Steaming  is  often  an  important  part  of  the  hand  process, 
and  probably  prevents  bacterial  decomposition.  The  leaves 
produced  in  small  cottage  holdings  are  often  put  upon 
plates  of  copper  and  held  over  the  fire.  In  some  dry  districts 
the  leaves  are  dried  by  tossing  them  in  the  sun. 

Cocoa  contains  theobromine,  an  alkaloid  similar  to  that 
in  tea,  associated  with  a  large  percentage  of  fat. 

Coffee. — Coffee  is  most  generally  raised  from  seed  sown 
in  nurseries,  but  for  economy  is  sometimes  sown  directly 
on  the  ground.  A  few  seeds  are  usually  sown  together, 
the  weaker  ones  being  removed.  The  land  should  be  well 
drained,  and  is  usually  situated  at  moderate  elevations  of 
two  thousand  to  five  thousand  feet  above  the  sea-level, 
where  the  rainfall  is  between  fifty  and  one  hundred  inches, 
and  the  temperature  55°  to  85°  Fahr.  Shade  is  a  most 
important  point  in  considering  coffee  plantations.  At 
least  temporary  shade  must  be  provided  for  the  seedlings. 


COFFEE  161 

Small  bushes  are  often  only  five  feet  apart,  but  under  the 
tree  system  as  much  as  fifteen  feet  is  sometimes  allowed. 
Catch  crops  are  not  infrequently  grown  along  with  the 
bushes.  Steep  hillsides  are  more  frequently  used  for 
coffee  plantations  than  tea  plantations,  but  where  they  are 
used  terracing  is  necessary.  In  coffee  districts,  the  hedges 
may  be  coffee  bushes,  but  such  do  not  yield  the  best  crop. 
Weeding  is  not  considered  an  important  point,  at  least  not 
so  important  as  in  tea  plantations.  The  coffee  plantation 
usually  comes  into  bearing  about  the  third  year  and  lasts 
for  about  forty  years.  The  fruits  are  usually  hand  picked, 
and  are  frequently  called  cherries,  whilst  the  seeds  contained 
are  alluded  to  as  berries.  The  coffee  fruit  consists  of  an 
external  pulp,  a  loose  tissue  called  "  parchment "  and  the 
silver  skin,  inside  of  which  is  the  coffee  berry.  The  fruits,  on 
removal  to  the  factory,  are  usually  thrown  into  water,  when 
the  ripe  cherries  sink  to  the  bottom.  The  ripe  cherries  are 
then  removed  to  a  pulping  machine,  whic^  tears  off  the  outer 
succulent  part.  This  part  is  mixed  up  with  water,  and  is, 
under  the  best  management,  carefully  preserved  and  used 
as  manure.  After  the  pulp  is  removed,  the  seeds  are  dried. 
The  "  parchment "  which  surrounds  the  seed  is  usually 
left  on,  and  the  seeds  with  their  "  parchment  "  dried  in 
the  sun  on  large  concrete  floors  resembling  tennis  courts. 
The  machines  specially  designed  for  removing  the  "  parch- 
ment "  are  usually  situated  near  some  large  town,  or  sea- 
port, since  the  weight  of  the  "  parchment  "  is  small,  and  the 
berries  carry  better  in  their  natural  coat.  The  produce  of 
one  acre  of  land  is  about  seven  cwt.  of  prepared  coffee, 
containing  about  10  or  12  per  cent,  of  moisture.  Compared 
to  this  the  total  weight  of  the  wet  berry,  at  plucking,  will  be 
about  1400  pounds,  with  about  270  pounds  of  "  parchment," 
and  yielding  1280  pounds  of  wet  pulp.  These  will  contain 
about  15  pounds  of  nitrogen  in  the  form  of  the  berry,  about 

2  pounds  of  nitrogen  in  the  form  of  "  parchment,"  and  about 

3  pounds  of  nitrogen  in  the  form  of  pulp.     There  will  be 
about  3  pounds  of  phosphoric  acid  in  the   coffee   berry, 
only  fractions  of  a  pound  in  the  skin  of   "  parchment," 

D.  II 


162  PLANT  PRODUCTS 

and  about  i  pound  in  the  flesh  of  pulp.  There  will  be  16 
pounds  of  potash  in  the  berry,  about  4  pounds  in  the  "  parch- 
ment, "  and  about  12  pounds  in  the  pulp.  The  return  of 
the  pulp  does  not  make  up  for  the  losses,  and  considering 
the  general  nature  of  the  soils  on  which  these  crops  are 
grown,  it  seems  highly  probable  that  potash  manure  should 
receive  more  consideration.  The  soils  on  which  the  coffee 
is  grown  are  usually  fairly  well  supplied  with  phosphates. 
It  is  quite  well  known  in  common  practice  that  nitrate  of 
potash  is  an  excellent  manure,  but  owing  to  its  expense 
the  amount  used  is  less  than  what  is  desirable.  There  is 
good  scope  here  for  the  use  of  increased  quantities  of  sulphate 
of  ammonia.  The  cultivation  both  in  Brazil  and  Madras 
are  similar  in  this  respect,  that  a  red  soil  is  much  preferred. 
In  Brazil  steep  slopes  are  not  employed  to  the  same  extent 
that  they  are  in  Madras.  In  some  kinds  of  treatment 
the  "  parchment  "  is  fermented,  and  removed  on  the  station, 
but  in  others  both  "  parchment  "  and  silver  skin  are  treated 
alike,  and  the  coffee  berry  is  sold  with  both  the  silver  skin 
and  the  "  parchment  "  adhering  to  it. 

Tannin. — The  subject  of  tanning  leather  is  treated  very 
fully  in  another  volume  of  this  series  (Bennett),  but  a  brief 
abstract  can  be  given  here  from  a  different  point  of  view. 
The  word  "  tannin  "  expresses  a  large  number  of  materials, 
which  have  all  the  common  property  that  they  are  used 
for  manufacturing  leather.  The  chief  sources  are  the  bark 
of  oak  and  many  other  trees,  together  with  myrobalans. 
Catechu  tannin  is  a  decomposed  product  of  Catechin, 
or  Khair,  the  extract  obtained  by  boiling  the  wood  of  acacia 
catechu  (mimosa  catechu).  As  a  rule  more  vigorous  trees 
yield  more  tannin,  but  the  character  of  the  soil  appears  to 
be  of  very  great  importance.  There  are  very  large  quantities 
of  oak  bark  grown  in  the  British  Isles  which  are  not  made 
much  use  of  owing  to  the  cost  of  collection.  This  subj ect  must 
be  treated  as  a  part  of  the  whole  question  of  forestry  of 
the  British  Isles.  Reafforestation  and  the  management  of 
woods  can  only  be  successfully  carried  out  if  all  possible 
sources  of  revenue  are  considered.  The  practical  management 


TANNIN  163 

of  the  collection  of  bark  in  the  British  Isles  will  be  closely 
connected  with  the  utilization  of  waste  wood  in  forest 
problems.  If  it  can  be  made  profitable  to  bark  the  trees, 
and  dispose  of  the  bark  for  tannin,  the  waste  wood  can  be 
distilled  for  the  production  of  a  much  better  quality  charcoal, 
and  in  practice,  therefore,  the  two  subjects  are  closely 
connected.  Calcareous  soils  probably  produce  more  tannin 
than  others,  and  since,  in  the  British  Isles,  it  is  only  the 
poorest  land  that  can  be  left  down  to  timber,  this  condition 
does  not  often  prevail.  The  proportion  of  tannin  appears 
to  be  greatest  in  bark  removed  about  April  or  May.  Charac- 
teristics of  the  tannins  are  that  they  reduce  Fehling  solution, 
are  precipitated  by  basic  lead  acetate,  give  a  blue-black 
colour  with  ferric  chloride,  and  are  precipitated  with  many 
bases.  Phlobaphenes  are  the  decomposed  products  of 
the  tannins  proper,  and  are  nearly  always  contained  in 
extracts  of  bark.  They  are  red-coloured  substances,  and 
though  almost  insoluble  in  water,  they  dissolve  in  solutions 
of  tannins.  Whilst  a  great  many  of  the  common  tannins 
contain  the  glucose  grouping,  such  is  by  no  means  invariably 
the  case.  Gall  nuts  are  very  rich  in  gallo-tannic  acid,  and 
may  contain  as  much  as  50  per  cent.  Ordinary  tannin, 
or  gallo-tannic  acid,  is  probably  a  compound  containing 
five  molecules  of  di-gallic  acid,  with  one  molecule  of  glucose. 
Catechin,  whilst  not  properly  tannin  itself,  is  easily  converted 
into  catechu  tannin,  a  change  which  takes  place  readily 
on  heating  to  120°,  or  slowly  by  merely  boiling  with 
water.  The  common  extracts  from  the  acacia  or  mimosa 
are  usually  mixtures  of  catechin  and  catechu  tannin.  The 
catechin  itself  is  used  medicinally  in  India,  or  as  a  chewing 
material.  Tannin  is  abundant  in  the  leaves,  in  all  active 
growing  parts  and  in  diseased  parts,  like  galls.  Any  irritation 
to  the  protoplasm  appears  to  increase  the  amount  of  tannin. 
Tannin  is  very  common  in  all  unripe  fruits,  but  disappears 
as  the  fruit  becomes  ripe. 

Rubber. — Rubber,  or  India  rubber,  is  the  material  which 
exudes  as  the  result  of  an  injury  to  many  particular  trees. 
Rubber  is  generally  derived  by  a  process  of  coagulation  from 


164  PLANT  PRODUCTS 

such  trees,  creeper,  shrubs,  etc.  The  laticiferous  system, 
which  is  distinct  from  the  sap-bearing  cell  system,  generally 
lies  between  the  outer  bark  and  cambium.  By  cutting 
through  the  bark  into  the  latex  cells  the  latex  is  obtained. 
This  operation  is  referred  to  as  tapping.  In  wild  rubber 
V-shaped  cuts  are  generally  made,  but  in  plantation  rubber 
the  trees  are  tapped  by  one  central  channel.  The  latex  is 
collected  in  a  cup  which  is  fastened  to  the  tree  below  the 
channel.  In  wild  rubber  the  sticky  latex  is  smoked  over  a 
fire  from  very  smoky  materials,  which  produce  much 
creosote,  tarry  matter,  acetic  acid,  etc.  Only  small  quantities 
are  treated  at  a  time,  and  gradually  a  substantial  piece 
of  rubber,  thirty  or  forty  pounds  weight,  is  produced. 
Plantation  latex  is  generally  coagulated  by  the  addition 
of  a  small  quantity  of  acetic  acid,  the  smoking  process  being 
carried  out  later  whilst  drying.  Recently  some  efforts  have 
been  made  to  produce  on  the  estates  themselves  a  crude 
pyro-ligneous  acid  obtained  by  the  distillation  of  waste  wood 
in  a  small  form  of  retort  (see  p.  131),  as  apparently  the 
single  application  of  crude  pyro-ligneous  acid  is  better  than 
successive  applications  of  acetic  acid  and  smoke.  The 
plantation  rubber,  being  produced  under  at  least  some 
partial  scientific  treatment,  is  much  superior  to  the  wild 
rubber.  The  crude  material  often  includes  much  resin 
and  other  vegetable  matter.  The  impure  varieties  require 
to  be  cleaned  in  a  special  machine.  Rubber,  when  stretched, 
does  not  return  to  its  original  condition,  but  remains  stretched 
for  some  time.  It  does  not,  however,  alter  in  volume. 
Rubber  appears  to  be  as  incompressible  as  water.  The  fact 
that  rubber  does  not  return  to  its  original  length  when 
stretched  is  commonly  alluded  to  as  hysteresis.  The 
freshly  cut  surfaces  of  rubber  readily  adhere  to  one  another. 
As  rubber  is,  strictly  speaking,  an  organic  gel,  it  absorbs 
water  freely,  and  may  increase  to  an  extent  of  twenty  five 
per  cent,  in  its  weight,  and  fifteen  per  cent,  in  its  volume. 
Many  organic  liquors,  like  petroleum,  coal  tar,  etc.,  are 
absorbed  by  rubber,  and  some  of  these  make  good  typical 
colloidal  solutions. 


RUBBER  165 

Vulcanization. — Heat  and  sulphur  produce  a  profound 
change  in  the  character  of  rubber,  known  as  the  process  of 
Vulcanization.  The  ordinary  slightly  vulcanized  rubber 
corresponds  to  a  formula  of  about  (C10H16)10S2.  but  the 
fully  vulcanized  rubber,  called  ebonite,  corresponds  to  about 
Ci0H16S2.  Mixing  is  an  important  part  of  the  preparation 
of  any  rubbers  for  commercial  purposes,  absolutely  pure 
rubber  having  little  utility.  Fillers  added  for  some  purposes 
are  such  materials  as  pyrites.  For  increasing  mechanical 
strength  zinc  oxide,  lime,  and  a  few  other  substances  are 
employed.  Asphalte  is  often  used  to  increase  the  resistance 
to  water.  Pigments  of  various  types  are  employed  to  alter 
the  colour.  "  Oil  substitutes  "  are  made  by  the  action  of 
sulphur  chloride  on  oils  (see  p.  136).  Vegetable  oils  are  used 
for  producing  low-grade  goods.  Reclaimed  or  waste  rubber 
is  also  much  used  for  admixture.  Rubber  tubing  is  generally 
made  either  by  pressing  together  the  edges  of  sheet,  or  by 
squirting  through  a  die.  Canvas  and  other  fabrics  built 
up  with  rubber  constitute  an  important  part  of  the  rubber 
industry,  for  all  purposes  where  special  strength  is  re- 
quired. 

Indigo. — Indigo  is  grown  in  Bengal,  but  is  also  grown 
very  largely  in  other  parts  of  India,  either  for  local  production 
of  dyestuff,  or  as  'a  green  crop  for  increasing  the  amount 
of  organic  matter  in  the  soil.  It  grows  very  freely,  and  does 
not  appear  to  need  very  much  manure,  but  the  problem 
of  the  relationship  of  manure  to  indigo  production  has  not 
been  by  any  means  completely  settled  as  yet.  The  plant 
is  cut  before  flowering,  and  tied  up  into  bundles.  It  is 
carried  as  quickly  as  possible  to  the  factories.  If  it  is  allowed 
to  ferment,  the  amount  of  dye  ultimately  obtained  is  reduced. 
The  bundles  are  filled  into  a  large  vat,  pressed  down  by 
bamboos .  The  whole  is  covered  with  water,  steeped  for  about 
ten  hours,  the  yellow-coloured  liquor  thrown  off,  and  beaten 
either  by  hand-working  bamboos,  or  by  a  kind  of  paddle 
wheel.  It  is  then  carried  to  a  boiler,  where  the  liquor  is 
heated.  The  indigo  is  filtered  off,  and  the  mass  dried. 
Sometimes  a  further  fermentation  is  allowed  to  take  place 


166  PLANT  PRODUCTS 

in  the  cake.  An  acre  of  land  produces  about  60  bundles 
of  indigo  plants,  each  about  five  feet  in  girth,  which  yield 
about  ten  pounds  of  indigo  cake.  Different  parts  of  the 
plant  yield  different  quantities  of  indigo,  the  upper  parts 
of  the  plant  being  most  prolific.  About  one-half  per  cent, 
of  crude  indigo  is  obtained,  representing  about  J  per  cent,  of 
real  indigotin.  The  actual  manufacture  usually  commences 
about  the  middle  of  June,  which  is  a  compromise,  as  the 
greatest  percentage  of  indigotin  does  not  correspond  with  the 
greatest  yield  of  crop.  New  varieties  are  also  being  intro- 
duced, which  are  said  to  be  able  to  yield  as  much  as 
twenty -five  pounds  of  crude  indigo  per  acre.  The  processes 
of  dyeing  are  described  by  Knecht  (see  p.  168). 

Fruit  Products. — Fruit  farming  is  practised  on  a  very 
large  scale  in  America,  where  considerable  areas  of  special 
land  are  covered  with  only  one  or  two  species.  In  Europe 
generally  more  variety  is  displayed.  In  Great  Britain 
fruit  growing  is  chiefly  of  the  market  garden  type,  although 
on  the  continent  of  Bui  ope  considerable  quantities  of  fruit  are 
grown  on  communistic  lines  in  the  villages  and  small  towns. 

The  manuring  of  fruit  trees  cannot  be  placed  on  the 
same  basis  as  the  fertilizing  of  other  crops.  Newly  planted 
trees  should  on  no  account  receive  large  applications  of 
concentrated  chemical  manure,  and  the  manuring  of 
established  trees  must  be  considered  individually.  The  great 
point  of  variation  in  the  requirements  of  fruit  trees  is  that 
of  the  supply  of  nitrogen ;  on  the  other  hand,  phosphates 
are  always  needed.  Many  trees  are  inclined  to  run  to  wood, 
whilst  others  become  stunted  from  bearing  too  heavy  crops. 
Old  or  unhealthy  trees  receive  much  benefit  fiom  nitrogenous 
fertilizers.  Grazing  by  poultry,  etc.,  in  the  orchard  is  also 
useful.  Apple  trees  are  especially  benefited  by  phosphates  ; 
a  dressing  of  basic  slag  in  the  autumn,  followed  by  a  small 
dressing  of  super-phosphate  in  the  spring  is  a  very  excellent 
method  of  procedure.  Kainit  makes  a  very  good  source 
of  potash  for  trees  that  are  growing  on  light  soils,  whilst 
many  growers  apply  nitrate  of  soda,  before  the  flowering 
time.  The  preservation  of  fruit  may  be  conducted  either 


FRUIT  167 

by  a  process  of  bottling,  in  which  the  fruit  is  placed  in  bottles 
along  with  water  with  or  without  sugar,  and  sterilized  by 
heating  with  steam,  or  by  making  into  jam.  In  the  bottling 
method,  so  long  as  bacteria  can  be  prevented  from  obtaining 
access  to  the  fruit  it  will  keep  indefinitely. 

Jam  and  similar  preserves  are  the  result  of  preserving 
fruit,  even  though  it  subsequently  comes  into  contact  with 
air,  and,  therefore,  bacteria.  The  object  aimed  at  in  producing 
such  a  type  of  preserve  is  to  obtain  a  solution  of  such  strength 
that  even  the  hardiest  bacterial  spores  undergo  plasmolysis. 
For  this  purpose  it  is  not  the  percentage  composition  of  the 
solution  that  is  the  determining  point,  but  the  molecular 
concentration,  and  26  per  cent,  of  glucose  will  be  equivalent 
to  50  per  cent,  of  cane  sugar  in  producing  a  definite  molecular 
concentration.  During  the  process  of  boiling  jam,  much  of 
the  cane  sugar  is  hydrolyzed,  and  the  molecular  concentration 
of  the  liquid  is  therefore  almost  doubled.  In  Japan  salt 
is  used  for  the  preservation  of  fruit,  and  the  French  dried- 
fruit  industry  is  an  important  one.  Fruit  can  be  dried  in  the 
sun,  or  by  artificial  heat.  The  gas  industry  is  now  supplying 
suitable  fruit-drying  ovens  heated  by  gas.  Crystallized 
fruit  is  produced  by  soaking  the  fruit  in  a  saturated  solution 
of  cane  sugar.  Many  of  these  processes,  however,  depend 
upon  secret  details,  which  often  involve  a  limited  amount  of 
fermentation  to  bring  out  special  flavours.  In  spite  of  the 
acid  flavour  of  many  fruits,  a  fair  proportion  of  sugar  is 
always  present  as  shown  in  Table  23.  An  apple,  for  example, 
contains  more  sugar  than  a  red  beetroot. 

TABLE  23. — SUGAR  IN  FRUITS, 

Apple      . .  . .          . .          . .          . .  12  per  cent. 

Apricot  ..  ..          ..          ..          . .          ..ii 

Banana  . .  . .          . .          . .          . .  20 

Blackberry  6 

Grape      . .  . .          . .          . .          . .          . .       8  to  26  per  cent. 

Orange  . .          » .          . .          . .          . .       6  per  cent. 

Peach 8 

Pear        . .  . .          . .          . .          . .          . .       9 

Plum       ..  ..          ..          ..          ..          ..15 

Raspberry  . .          . .          . .          . .          . .       5 

Strawberry  . .          . .          . .          . .          . .       6 


168  PLANT  PRODUCTS 

Injuries  from  Chemical  Fumes. — Near  industrial 
towns  it  not  infrequently  happens  that  fumes  of  sulphuric 
and  hydrochloric  acids  do  much  harm  to  fruit  trees.  Currant 
bushes  appear  to  be  very  susceptible  to  such  fumes,  but 
rhubarb  is  nearly  as  much  injured  and  beans  and  potatoes 
in  market  gardens  are  also  sometimes  damaged.  Whilst  the 
removal  of  the  acid  vapours  is  to  be  desired  from  every 
point  of  view  yet  for  prompt  protection  something  can  be 
done  by  sprays.  At  the  author's  suggestion  experiments 
are  being  tried  with  a  spray  made  from  one  pound  of  pre- 
cipitated chalk  in  ten  gallons  of  water  (=i  per  cent.)  applied 
with  the  ordinary  knapsack  potato  sprayer  to  the  upper 
surface  of  the  leaves  of  such  plants  as  show  signs  of  black 
spots.  So  far  the  experiments  are  very  promising. 

REFERENCES   TO   SECTION  V 

Mann,  "The  Renovation  of  Deteriorated  Tea,"  Agric.  Journ.  India, 
1906,  p.  84. 

Coombs,  Alcock  and  Sterling,  "  Comparative  Tests  with  Mangrove  and 
Wattle  Barks,"  Journ.  Soc.  Chem.  Ind.,  1917,  p.  188. 

Stevens,  "  The  Function  of  Litharge  in  the  Vulcanization  Process," 
Journ.  Soc.  Chem.  Ind.,  1915,  p.  524. 

Davies,  "  Hysteresis  Tests  for  Rubber,"  Journ.  Soc.  Chem.  Ind.,  1914, 
P.  992. 

Stevens,  "  The  Vulcanization  of  Rubber  Agents  other  than  Sulphur," 
Journ.  Soc.  Chem.  Ind.,  1917,  pp.  107,  872. 

Eaton  and  Grantham,  "  Vulcanization  Experiments  on  Plantation 
Para  Rubber,"  Journ.  Soc.  Chem.  Ind.,  1915,  p.  989 ;  1916,  pp.  715,  1046. 

Eaton  and  Day,  "  Estimation  of  Free  and  Combined  Sulphur  in 
Vulcanized  Rubber,  and  the  Rate  of  Combination  of  Sulphur  with  Plan- 
tation Para  Rubber,"  Journ.  Soc.  Chem.  Ind.,  1917,  p.  1 6. 

Whitby,  "  A  Comparison  of  the  Brazilian  and  Plantation  Methods  of 
preparing  Para  Rubber,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  493. 

Luff,  "  Some  Aspects  of  the  Synthesis  of  Caout-chouc,"  Journ.  Soc. 
Chem.  Ind.,  1916,  p.  983. 

Porritt,  "  Some  Notes  on  the  Raw  Materials  used  by  the  Rubber 
Manufacturer,"  Journ.  Soc.  Chem.  Ind.,  1916,  p.  989. 

Mann,  "Assam  Rubber,"  Agric.  Journ.  India,  1906,  p.  390. 

Fowler,  "  Bacterial  and  Enzyme  Chemistry,"  p.  245.     (Arnold.) 

Basu,  "Orange  Cultivation,"  Agric.  Journ.  India,  1906,  p.  62  ;  Wright, 
"  Hevea  Braziliensis. "  (Maclaren.) 

Joshi,  "Orange  Cultivation,"  Agric.  Journ.  India,  1907,  p.  62. 

Knecht,  Rawson  and  Lrewenthal,  "A  Manual  of  Dyeing." 

Money,  "Tea  Cultivation."     (Whittingham.) 

Crowther  and  Ruston,  "  Effect  upon  Vegetation  of  Atmospheric 
Impurities,"  Journ.  Agric.  Science,  iv.,  p.  25. 


SECTION  VI.— FERTILIZERS  IN  RELATION 
TO   PLANT  PRODUCTS 

DIFFERENT  crops  require  different  fertilizers  for  their  develop- 
ment, but  it  must  not  be  imagined  that  the  fertilizers 
required  for  a  particular  crop  are  specific  types  of  mixtures. 
Some  general  conceptions  of  the  relationship  between  the 
fertilizers  and  the  crops  are  possible,  however.  Proper 
manures  for  any  particular  crop  always  depend  upon  a 
very  large  number  of  circumstances,  many  of  which  may  be 
peculiar  to  the  district,  and  even  to  the  particular  field. 
Mixtures  sold  as  "  turnip  manure,"  "  potato  manure,"  etc., 
can  only  give  a  kind  of  general  average,  and  it  is  the  business 
of  the  farmer  to  understand  his  own  land,  and  not  leave 
the  management  of  it  in  the  hands  of  somebody  who  has 
never  seen  it.  No  proper  idea  of  the  manure  required 
for  the  crop  can  be  obtained  without  a  knowledge  of  the 
system  of  rotation  adopted,  and  although  this  may  also 
be  worked  down  into  general  averages,  again  it  is  not  a 
subject  of  which  the  farmer  can  leave  the  details  to  a  general 
average  of  the  country,  but  he  must  adopt  his  manure  to 
his  own  particular  requirements.  Moreover,  some  land  may 
be  naturally  in  a  high  condition,  whilst  other  land  may 
be  in  a  very  low  condition.  One  farmer  may  be  justified 
in  building  up  the  fertility  of  the  soil  to  a  much  higher 
condition,  whilst  another  would  not  be  justified  in  making 
any  such  effort.  At  the  present  time,  when  prices  are  going 
upwards,  and  while  the  relationship  of  labour  to  the  farm 
is  being  completely  altered  in  the  British  Isles,  ideas  which 
were  formerly  sound  have  become  quite  impracticable.  The 
question  of  the  markets,  the  supply  of  labour,  and  the  rent 
of  the  land  will  always  be  in  need  of  careful  consideration. 


1 70  PLANT  PRODUCTS 

Contrasting  the  state  of  affairs  in  the  British  Isles,  where 
there  is  a  fairly  conservative  system  in  vogue,  with  that 
prevailing  in  the  more  recently  developed  parts  of  the 
United  States,  where  the  farmer  is  largely  living  upon 
capital  originally  stored  in  the  soil,  and  also  with  that 
prevailing  among  some  of  the  aboriginal  tribes  of  India, 
who  merely  burn  a  patch  of  waste  land  and  move  on,  and 
taking  into  account  the  relatively  new  lands  of  Australia, 
we  may  see  that  the  system  of  farming  will  have  much 
effect  upon  the  suitability  of  fertilizers.  The  Western 
American  farmer  may  often  go  on  growing  maize  and  wheat 
and  burning  the  straw,  and  putting  hardly  any  manure  upon 
the  land.  For  a  time  such  a  process  may  be  suitable,  but  it 
cannot  represent  a  permanent  condition  of  agriculture.  The 
type  of  pioneer  farmer  on  the  Western  parts  of  America 
only  represents  a  particular  period  in  the  opening  up  of  the 
country.  The  American  pioneer  has  turned  out  the  redskin, 
only  to  be  in  his  turn  replaced  by  a  farmer  who  works  a 
mixed  farm.  The  aboriginal  Indian  has  originally  replaced 
the  wild  animals  of  the  forests,  and  he  himself  has  been 
turned  out  by  the  more  progressive  Hindu,  who  to-day  is 
being  blamed  for  his  relatively  unprogressive  character,  and 
the  Australian  squatter,  with  his  sheep,  has  turned  out  the 
aboriginal,  who  only  hunted  the  kangaroo,  and  the  squatter 
is  feeling  aggrieved  because  he  is  being  replaced  by  the  so- 
called  "  free  selector."  Agriculture  will  need  to  progress 
in  all  countries,  and  what  is  suitable  for  one  step  in  the 
process  is  not  at  all  suitable  for  another  step.  Further,  as 
agriculture  passes  through  the  stage  of  mixed  farming,  it 
goes  further,  and  produces  the  intensive  farmer,  who 
endeavours  to  produce  the  maximum  amount  of  food  from 
his  land,  and  we  now  have  to  consider  the  question  of  the 
industrialization  of  agriculture,  so  as  to  induce  still  further 
improvement  in  the  manufacture  of  plant  products  from 
the  soil.  Although  it  is  quite  impossible  to  set  down  any 
rigid  relationship  between  fertilizers  and  plant  products, 
it  is,  nevertheless,  quite  feasible  to  adopt  some  general 
principles. 


FERTILIZERS  AND  PLANT  PRODUCTS      171 

The  Carbohydrate  Producing  Crops. — Wheat  is 
one  of  the  most  important  plants  grown  in  all  countries  of 
advanced  agriculture,  as  part  of  a  system  of  totation  of 
four  or  more  years.  Wheat  is  particularly  suited  to  ploughed- 
up  land  which  has  borne  grass  or  clover,  or  mixtures  of  the 
two.  In  such  cases  little  fertilizer  is  necessary,  a  top 
dressing  of  sulphate  of  ammonia,  to  the  extent  of  half  a 
hundredweight  per  acre  in  the  winter  and  spring,  being 
generally  considered  sufficient.  When  many  white  crops 
are  grown  with  a  degree  of  frequency  beyond  that  of  once 
in  four  years,  some  phosphatic  manures  will  generally  be 
found  necessary,  and  on  the  lighter  soils  some  potash. 
Oats  also  require  comparatively  little  manure  when  grown 
after  a  hay  crop .  Barley,  when  required  for  malting  purposes, 
should  have  comparatively  little  nitrogenous  manure, 
though  when  required  for  feeding  purposes  more  may  be 
supplied.  Phosphates  are  particularly  desirable  for  purposes 
of  producing  sound  ripening,  as  alluded  to  below.  Potatoes 
are  grown  on  such  a  great  variety  of  soils  that  it  is  difficult 
to  lay  down  any  particular  rules,  excepting  that  farmyard 
manure  is  generally  desirable,  although  in  some  districts 
no  farmyard  manure  is  employed,  potatoes  being  grown 
after  about  two  years  clover.  A  good  deal  of  the  advantage 
of  using  farmyard  manure  for  potatoes  is  purely  physical, 
as  the  potato  does  not  develop  good  root  system  unless  the 
soil  is  very  open,  and  even  actually  hollow.  Sulphate  of 
ammonia  is  generally  preferable  to  nitrate  of  soda  and 
super-phosphate  is  often  better  than  basic  slag.  L/ime  is 
also  generally  considered  unsuited  for  potatoes.  Excessive 
nitrogenous  manure  causes  the  potatoes  to  produce  less 
starch,  and  more  nitrogenous  and  fibrous  tissue.  In  garden 
cultivation  of  potatoes  working  the  land  so  as  to  produce 
a  somewhat  hollow  structure  is  useful,  as  it  induces  the 
roots  to  go  down  after  water,  and  leaves  the  soil  loose  for  the 
development  of  the  tubers.  Sugar-producing  crops  are  often 
more  exhaustive.  Swedes  and  mangolds  require  much 
nitrogenous  as  well  as  phosphatic  manure.  A  standard 
dressing  is  used  for  mangolds  at  Cockle  Park,  containing 


172  PLANT  PRODUCTS 

eighty  pounds  of  nitrogen,  forty  pounds  phosphoric  acid, 
one  hundred  and  fifty  pounds  potash,  and  two  hundred 
pounds  common  salt,  a  relatively  somewhat  expensive 
mixture.  The  root  crops  in  general,  when  grown  with  a 
large  amount  of  nitrates,  especially  nitrate  of  soda,  decrease 
in  food  value,  the  plants  being  of  a  rather  watery,  poor 
feeding  quality.  Potash,  which  is  so  essential  for  the 
mangold  crop,  can  be  economized  to  a  partial  extent  by  the 
use  of  sodium  salts.  A  particularly  useful  waste  industrial 
product  is  a  mixture  of  calcium  sulphate  and  sodium  chloride, 
obtained  from  some  salt  works.  Where  sodium  chloride 
is  desirable  for  cultivation,  as  it  is  in  the  case  of  mangolds, 
the  sodium  has  the  tendency  to  render  the  clay  sticky,  but 
an  admixture  of  calcium  sulphate  overcomes  this  difficulty, 
as  it  prevents  the  formation  of  colloidal  compounds. 

The  Leguminous  Crops  obtain  much  of  their  nitrogen 
from  the  atmosphere,  and  therefore  do  not  require  nitro- 
genous manure,  excepting  very  small  quantities  to  get  over 
their  early  stages,  when  they  are  particularly  subject  to 
the  attack  of  all  kinds  of  pests.  Small  quantities  of  nitro- 
genous manure  enable  them  to  get  out  of  the  reach  of  many 
of  their  enemies  at  a  period  when  their  capacity  for  obtaining 
nitrogen  from  the  air  is  very  small  indeed.  They  are 
particularly  dependent  upon  lime,  potash,  and  phosphoric 
acid.  The  importance  of  clover  in  the  hay  crop  as  part  of 
the  rotation  has  been  recognized  from  the  earliest  times, 
the  procedure  being  known  to  the  Romans.  This  system 
is  also  adopted  in  tropical  countries,  like  India,  where  a 
leguminous  crop  is  grown  either  mixed  with  one  of  the  millets, 
or  as  a  separate  part  of  the  rotation.  The  increase  in  the 
nitrogen  content  of  the  soil,  by  the  growth  of  clover,  has 
been  already  alluded  to  (see  p.  81).  Among  the  different  kinds 
of  clover,  the  wild  white  clover  has  been  found  particularly 
suitable  for  development  in  the  pastures.  Where,  however, 
the  conditions  of  the  soil  are  of  a  rather  moist  character, 
probably  the  wild  red  clover  is  equally  suitable.  There  is 
a  great  difference  between  growing  mixed  crops  of  herbage 
and;!  growing  a  single  crop  in  the  ordinary  way.  Where 


FERTILIZERS   AND  PLANT  PRODUCTS      173 

there  are  many  species  all  struggling  with  one  another,  hardy 
varieties  are  essential,  hence  the  wild  forms  of  the  clover 
plant  are  particularly  suited  for  development  in  a  pasture. 
Seed  which  has  been  sown  on  well-tilled  land  for  many 
generations  has  no  necessity  to  struggle  with  other  species, 
is  weakened  in  the  process,  and  is  no  longer  able  to  fight  for 
itself.  There  is  a  great  difference  between  land  which  is 
laid  up  for  hay  and  land  which  is  down  to  permanent 
pasture.  The  species  which  will  establish  themselves  in 
the  two  kinds  of  soil  are  not  the  same,  and,  therefore,  it  is 
not  desirable  that  land  should  be  sometimes  cut  for  hay  and 
sometimes  grazed,  since  no  permanent  equilibrium  would 
result.  In  the  Tree  Field  experiment  at  Cockle  Park  the 
use  of  basic  slag  has  completely  altered  the  physical  properties 
of  the  soil,  the  deep  roots  of  the  clover  having  altered  the 
physical  texture  of  the  soil  down  to  about  twelve  inches  in 
depth.  Somewhat  similar  to  the  action  of  wild  white 
clover  in  the  British  Isles  is  the  action  of  the  celebrated 
dub  grass  of  India,  a  grass  which  possesses  a  creeping  stem, 
which  opens  up  the  soil  in  a  more  efficient  way  than  many 
other  forms  of  grass.  Where  land  is  cut  for  hay  for  any  period 
of  time,  one-sided  manures  become  impractical.  Well- 
balanced  manuring  is  far  more  important  for  this  purpose 
than  for  crops  which  are  grown  in  a  rotation.  Generally 
speaking,  it  is  the  heavy  land  which  should  be  down  to  grass, 
and  such  lands  will  not  usually  require  much  potash.  The 
lighter  lands  should  properly  be  ploughed,  and  not  be 
permanently  down  to  grass  at  all.  Grass  should  only  be 
part  of  the  ordinary  rotation  on  such  lands,  where  it  should 
be  "  seeds  hay  "  for  one  or  more  years.  Where  land  is  down 
permanently  to  hay,  very  generous  manuring  is  necessary. 
At  Cockle  Park,  on  Palace  L,eas  Field,  which  has  been  cut 
for  hay  for  over  twenty  years,  slag  has  been  found  very 
profitable,  but  is  not  yielding  such  big  crops  as  more  mixed 
systems  of  manuring.  For  obtaining  large  crops  of  hay, 
farmyard  manure  is  almost  essential,  although  very  fair  crops 
have  been  obtained  by  phosphatic  manures,  supplemented 
by  potassic  manures.  The  relative  feeding  values  of  the 


174  PLANT  PRODUCTS 

hay  so  obtained  show  much  variation.  The  amount 
of  albuminoids  in  the  hays  so  produced  are  much  greater 
where  phosphatic  manures  are  applied,  the  best  results  being 
obtained  with  both  phosphatic  and  potassic  manures. 
Generally  speaking,  the  hays  of  the  higher  feeding  values 
have  been  those  obtained  by  both  slag  and  potash,  even 
though,  on  the  whole,  the  soil  is  towards  the  heavy  side. 
I^and,  however,  which  is  down  to  pasture,  will  only  require 
much  smaller  dressings,  and  occasional  quantities  of  lime 
and  basic  slag,  giving  about  an  average  of  three  hundred- 
weight of  lime  and  one  hundredweight  of  basic  slag  for 
each  year.  This  is  for  permanent  pasture,  which,  by  rights, 
would  only  be  on  the  heavier  lands.  A  large  amount  of 
weeds,  especially  buttercup  and  wild  geranium,  are  indications 
of  excessive  richness,  produced  by  cake  feeding,  which  has 
never  been  supported  by  proper  supplies  of  phosphatic 
manures.  For  pasture  lands,  nitrogenous  manures  are 
generally  unsatisfactory,  as  sufficient  nitrogen  is  supplied 
by  the  droppings  of  the  cattle. 

Sugar  Cane. — Sugar  cane,  like  most  of  the  sugar- 
producing  crops,  requires  considerable  quantities  of  nitro- 
genous fertilizers.  Owing  to  its  long  period  of  growth, 
these  should  be  of  the  slow-acting  type.  For  the  ratoon  crops 
there  is  some  difference  of  opinion  as  to  whether  the  residues 
of  the  manuring  of  the  previous  crop  can  be  economically 
replaced  by  more  active  forms  of  nitrogen.  On  the  lighter 
soils  potash  is  also  very  necessary.  The  chemical  activities 
of  the  soil  are  greater  in  hot  than  in  cold  climates.  The 
decay  of  organic  matter  takes  place  with  great  rapidity  in 
hot  climates,  and  even  after  ploughing-in  green  crops  for 
many  years  the  accumulation  of  organic  matter  will  not 
reach  the  amount  of  a  single  green-  manuring  in  colder 
climates.  As  carbon  dioxide  is  produced  in  the  soil  at  a 
greater  rate  than  in  cold  climates,  the  general  amount  of 
carbonic  acid  dissolved  in  the  soil  water  will  be  greater, 
in  spite  of  the  warm  weather.  Hence  weathering  of  soil 
will  take  place  more  rapidly  in  tropical  climates  than  in 
cold  climates. 


FERTILIZERS   AND  PLANT  PRODUCTS      175 

Cotton  having  a  somewhat  shorter  period  of  growth, 
and  producing  a  seed  rich  in  mineral  matter,  needs  the 
application  of  larger  quantities  of  fertilizers.  Phosphates 
and  organic  nitrogen  manures  are  very  valuable  for  this 
type  of  crop,  and  sulphate  of  ammonia  can  be  also  used 
profitably  here. 

Tea  being  a  perennial  crop  has  rather  more  resemblance 
to  hay  than  many  of  the  other  types  of  crop.  Whilst  a 
certain  amount  of  nitrogenous  manure  is  desirable,  excessive 
amounts  tend  to  produce  an  inferior  quality  of  leaf.  Some 
of  those  who  experimented  in  the  use  of  sulphate  of  ammonia 
obtained  rather  unsatisfactory  results  at  first.  The  reason 
for  this  was  that  excessive  quantities  were  supplied  in  an 
unsuitable  manner.  Where  an  ample  supply  of  organic 
manures  can  be  obtained,  sulphate  of  ammonia  is  not 
so  necessary,  but  in  many  situations  small  and  cautious 
applications  of  sulphate  of  ammonia  will  probably  be  found 
useful  (see  Bald,  p.  177). 

Coffee  is  a  somewhat  exhaustive  crop,  and  requiies 
a  fair  amount  of  nitrogen,  phosphates,  and  potash. 

Succulent  Crops. — The  general  effect  of  nitrogenous 
manuring  is  to  delay  the  ripening  of  the  plant,  and  to  produce 
a  large  quantity  of  green  material.  Nitrogenous  manures 
tend  to  produce  large  quantities  of  succulent  matter,  but 
do  not  tend  to  produce  flowers,  fruit,  and  seed. 

These  manures  are,  therefore,  especially  valuable  for 
such  crops  as  lettuces,  cabbages,  mangolds,  tea,  etc.  The 
phosphatic  manures  are  generally  characterized  by  the 
production  of  deep  roots,  and  it  is  for  this  reason  that 
the  shallow-rooted  crops  need  considerable  quantities  of 
phosphates,  because  they  have  no  deep  root  system  to  go 
after  plant  food',  and  require  something  to  strengthen  this 
system.  Potash  manure  tends  rather  to  the  production 
of  seeds  and  flowers,  but  does  not  help  root  development  to 
any  very  large  extent,  but  it  has  no  delaying  action,  in  the 
same  way  as  the  nitrogen.  Development  of  deep  roots  will 
also  depend  upon  the  position  of  the  water  supply.  Deep 
water  will  encourage  deep  rooting,  and  surface  water  will 


176  PLANT  PRODUCTS 

encourage  surface  roots.  The  influence  of  the  different 
manures  upon  the  composition  of  pasture  is  very  marked 
indeed.  In  the  experiments  at  Tree  Field,  Cockle  Park, 
the  addition  of  phosphatic  manures  not  merely  increased  the 
amount  of  grazing,  but  also  increased  the  feeding  value  of 
the  grass  that  was  cut  from  this  pasture.  The  phosphoric 
acid  was  more  than  doubled  in  amount,  the  potash  increased 
about  80  per  cent.,  and  the  nitrogen  increased  about  the 
same  figure,  although  no  nitrogen  or  potash  was  applied. 
The  addition  of  lime  produced  comparatively  little  effect, 
either  in  the  quality  or  quantity  of  the  herbage,  since  this 
was  not  the  material  which  was  most  urgently  needed.  This 
large  increase  in  the  percentage  composition  of  nitrogen  and 
potash  as  well  as  phosphoric  acid  has  been  brought  about  by 
the  application  of  a  phosphatic  manure.  As  explained 
before,  in  the  case  of  the  hay  crop  more  general  manurial 
treatment  is  desirable,  and  the  results  are,  therefore,  not 
so  striking,  but  the  use  of  a  manure  like  sulphate  of  ammonia 
does  not  increase  the  albuminoids  in  the  hay  to  any  appreci- 
able extent.  In  the  case  of  the  swede  turnip  crop,  manures 
containing  little  phosphates  produce,  on  the  whole,  swedes 
which  contain  less  sugar  than  those  manures  which  are 
deficient  in  potash  and  nitrogen. 

Food  and  Growth. — When  very  wet  periods  intervene 
there  is  a  liability  to  considerable  loss  of  nitrogen  in  the 
form  of  nitrates,  and  under  these  circumstances  only  a 
portion  of  the  nitrogen  supplied  will  go  into  the  crop. 
Plants  having,  therefore,  a  short  period  of  growth  are  much 
more  likely  to  miss  a  large  fraction  of  the  fertilizing  materials 
than  those  very  slow  growing  crops  that  only  reach  maturity 
after  many  months  of  growth.  In  tropical  climates,  where  the 
growth  of  the  plant  and  the  chemical  changes  in  the  soil  are 
both  very  rapid,  the  manure  has  a  greater  fertilizing  efficiency 
than  in  cold  climates.  Where  soils  are  excessively  cold,  or 
excessively  hot,  full  utilization  of  the  fertilizers  is  impossible. 
Water  and  manure  must  be  considered  together.  To  some 
extent,  a  large  supply  of  moisture,  either  from  the  sky  or 
by  means  of  irrigation,  will  make  up  for  a  deficiency  in  the 


FERTILIZERS  AND   PLANT  PRODUCTS      177 

supply  of  fertilizer  supplied.  In  wet  climates,  like  Ireland, 
unsatisfactory  soils  and  insufficient  manure  may  produce 
partially  successful  results,  which  could  not  possibly  be 
imitated  in  a  drier  and  colder  climate.  Accumulations  of 
either  acidity  or  alkalinity  are  harmful.  Acidity  is  more 
frequently  produced  by  excessive  quantities  of  organic 
matter  than  by  any  accumulation  of  mineral  acid,  although 
the  use  of  sulphate  of  ammonia  in  large  excess  may  pro- 
duce the  latter  result.  Alkalinity  is  produced  by  the  appli- 
cation of  lime  or  by  the  residues  of  soda  left  from  excessive 
applications  of  nitrate  of  soda  or  by  natural  decomposition 
of  soda  felspar  in  the  soil.  The  removal  of  acidity  is 
generally  obtained  by  the  use  of  lime,  while  the  removal  of 
alkalinity  can  be  accomplished  by  the  use  of  super-phos- 
phates and  gypsum.  In  the  former  case  the  neutralization 
of  the  acid  is  due  to  the  calcium  bi-carbonate  formed  from 
lime,  carbon  dioxide,  and  water.  In  the  latter  case  sodium 
carbonate,  sodium  humate,  or  soluble  sodium  silicate  is 
decomposed  by  calcium  sulphate  with  the  formation  of 
neutral  sodium  sulphate  and  other  harmless  substances. 
Cultivation  is  one  of  the  best  means  by  which  most  is  made  of 
the  fertilizing  ingredients  in  the  soil,  or  supplied  in  the  form 
of  fertilizers.  Without  efficient  cultivation,  full  utilization 
of  the  fertilizers  will  always  be  impossible. 

REFERENCE   TO   SECTION  VI 

"  Compound  Manures,"  Journ.  Board  of  Agriculture,  1915—16,  p.  675. 

Clouston,  "Artificial  Fertilizers  for  Cotton,"  Agric  Journ.  India,  1908, 
p.  246. 

Bald,  "Experiments  in  Manuring  on  a  Tea  Estate,"  Agric.  Journ. 
India,  1913,  p.  157;  1914,  p.  182 


D.  12 


PART  IV.— THE   PRODUCTION  OF  MEAT 

SECTION  I.— MANURING  FOR  MEAT 

To  make  the  most  of  all  plant  products  is  to  make  the  most 
efficient  use  of  agriculture.  Experience  in  all  lines  of  business 
has  shown  that  there  are  certain  methods  common  to  all  com- 
mercial concerns,  and  the  plan  to  industrialize  agriculture  can 
only  mean  the  adoption  in  agriculture  of  the  lessons  learnt 
in  promoting  efficiency  in  other  businesses .  Industrialization 
of  agriculture  is,  however,  no  new  thing  ;  it  has  been  done 
before.  The  large  Collieries  in  County  Durham  (see  p.  209), 
for  example,  employ  managers  and  sub-managers  for  large 
estates,  and  many  colonial  concerns  are  also  worked  in  the 
same  way.  Much  land  in  the  British  Isles  is  unsuited  to 
corn,  and  hence  the  industrial  improvement  of  agriculture 
will  largely  turn  on  the  improvement  and  development 
of  manuring  for  meat  and  the  production  of  cheese.  One 
strong  point  in  favour  of  industrialization  is  that  the  manager 
of  a  large  concern  can  buy  and  sell  on  better  terms  than 
the  manager  of  a  small  concern.  The  chief  difficulty  of 
the  farm  lies  in  the  immense  difference  between  what  the 
consumer  pays  and  what  the  farmer  gets.  Sometimes  the 
farmer  does  not  receive  one-third  of  what  the  consumer 
pays,  and  the  management  of  an  industrialized  farm  can 
check  this  source  of  loss  (see  p.  209). 

Manuring  for  Meat. — The  change  from  pioneer  types 
of  agriculture  to  general  conditions  of  mixed  farming  needs 
stock  feeding  as  an  essential  part,  since  such  conditions  of 
general  farming  combine  two  entirely  distinct  objects, 
namely,  stock  and  crop  production.  The  amount  of  meat 
that  can  be  produced  from  an  area  in  pasture  is  Jess  than  that 


MANURING  FOR  MEAT  179 

produced  from  an  equal  area  of  mixed  farming,  whilst  that 
area,  if  entirely  cultivated,  would  not  be  so  productive, 
unless  the  farmyard  manure  could  be  replaced.  The 
greatest  efficiency,  therefore,  can  be  produced  by  combining 
crop  and  stock  production.  The  first  efforts  to  measure 
meat  production  in  terms  of  fertilizers  were  those  initiated 
in  Tree  Field,  Cockle  Park,  by  Dr.  William  Somerville, 
continued  by  Professor  Middleton  and  Professor  Gilchrist, 
and  repeated  in  other  places  with  similar  results.  The 
general  effect  of  the  use  of  basic  slag  on  the  heavy  types  of 
clay  land  have  been  to  very  markedly  increase  the  amount 
of  meat  produced,  as  measured  by  means  of  the  sheep 
grazing.  After  allowing  for  the  cost  of  manure  the  profits 
are  several  times  larger  than  the  rental.  By  employing 
larger  plots,  grazed  by  mixed  cattle  and  sheep,  better  results 
have  been  obtained.  The  most  economical  system  has  proved 
to  be  the  application  of  ten  hundredweight  of  basic  slag, 
followed  by  five  hundredweight  every  three  years.  Where 
the  animal  is  set  grazing  it  may  be  regarded  as  a  machine 
for  converting  low-grade  into  high-grade  food,  that  is,  food 
of  low  value  to  human  beings  is  converted  into  food  suitable 
for  human  consumption. 

In  this  process  of  conversion  of  crude  materials  into 
articles  valuable  for  human  purposes,  considerable  changes 
have  to  take  place  in  the  animal  body.  Grazing  beasts  may 
generally  be  said  to  be  composed  of  about  9  per  cent,  bone, 
40  per  cent,  muscle,  24  per  cent,  fat,  and  27  per  cent,  blood, 
intestines,  and  other  offal.  Of  this,  the  muscular  part, 
together  with  the  fat,  forms  the  chief  eatable  material. 
The  actual  amount  of  human  food  is  roughly  about  one-half 
of  the  total  beast.  At  birth,  young  animals  contain  large 
quantities  of  water,  about  80  to  85  per  cent.,  but  in  a  very 
fat  beast  the  amount  of  water  will  only  be  about  40  per  cent. 
If  the  various  parts  of  the  beast  are  corrected  for  the  amount 
of  water  contained,  there  will  be  about  6  per  cent,  of  dry 
material  in  the  bones  of  an  average  farm  animal,  in  the 
muscle  13  per  cent.,  in  the  fat  20  per  cent.,  leaving  about 
7  per  cent,  dry  matter  in  the  offal,  the  whole  body  containing 


i8o  PLANT  PRODUCTS 

about  46  per  cent,  of  dry  material,  the  rest  being  water. 
The  fat  of  the  animal  body,  like  most  of  the  other  compounds 
of  this  group,  is  a  glycerine  ester,  and  the  fatty  acids  are 
stearic,  palmitic,  and  oleic.  The  fat  of  the  animal  body  as 
separated  by  the  butcher  consists  of  the  chemical  fat, 
enclosed  in  membranes.  In  a  fat  beast  the  amount  of 
membrane  in  the  fat  is  comparatively  small,  but  in  a  lean 
beast  it  might  amount  to  one-quarter  of  the  weight  of  the 
fat.  Carbohydrates  are  only  present  to  a  very  small 
extent.  Small  quantities  of  dextrose  are  always  present 
in  the  blood,  to  the  amount  of  about  0*1  to  0*2  per  cent., 
any  excess  of  carbohydrate  being  stored  in  the  liver.  The 
proteins  have  been  fully  described  (see  Bennett,  Bibliography) . 
During  the  life  of  the  animal,  the  chief  metabolic  changes 
consist  in  the  hydrolysis  of  the  proteins,  fats,  and  sugars, 
followed  subsequently  by  their  oxidation.  The  major  part 
of  the  proteins  in  the  animal  body  exist  in  the  form  of  the 
organs,  and  are  semi-permanent.  The  remaining  portion 
is  temporary,  and  undergoes  rapid  chemical  changes.  It 
is  this  portion  which  supplies  the  vital  energy  necessary 
to  the  beast.  The  chief  effect  of  setting  an  animal  to  perform 
work  is  to  increase  the  rate  of  chemical  breakdown  of  the 
fats  and  carbohydrates.  It  is  only  overworking  which 
will  produce  any  large  breakdown  of  the  animal  proteins. 
Stimulants,  excitement,  and  the  consumption  of  salt  increase 
the  amount  of  protein  decomposed  in  the  animal  body. 
The  heat  that  is  lost  by  the  animal  is  chiefly  lost  by  radiation 
and  conduction  from  the  surface  and  by  evaporation  from 
lungs  and  skin.  The  evaporation  from  the  lungs  depends 
upon  the  amount  of  breathing,  and,  therefore,  upon  the 
amount  of  exercise. 

When  the  proteins  are  broken  down  in  the  animal  body, 
during  the  process  of  digestion,  they  are  resolved  into  the 
corresponding  amino  acids.  The  number  of  these  amino 
acids  that  are  necessary  is  comparatively  very  limited. 
Most  of  the  amino  acids  into  which  the  proteins  are  broken 
down  in  digestion  are  aliphatic,  some  mono-carboxylic, 
and  some  di-carboxylic.  Some  of  them  are  mono-ammo 


MANURING  FOR  MEAT  181 

acids  and  some  di-amino.     Some  of  them  are  straight,  and 
some  of  them  are  branched.    An  important  cyclic  compound 
is  indole,  which  the  animal  body  does  not  seem  capable  of 
synthesizing.     A  common  hydrolytic  product  of  the  break- 
down of  some  proteins  is  tryptophane,  which  contains  the 
indole  ring.     The  proper  utilization  of  the  proteins  absorbed 
from  the  food  appears  to  depend  upon  minute  traces  of 
substances  which  are  known  as  food  hormones.     little  is 
known  about  the  exact  character  of  these  bodies,  although 
some  are  compounds  of  pyridine.     When  tryptophane  is 
broken  up  in  the  animal  body,  it  is  probably  excreted  as 
skatole,  which  is  of  a  purgative  character.     One  of  the 
results  of  feeding  excessive  quantities  of  protein  material 
is  usually  to  produce  a  loosening  effect.    This  is  probably, 
at  least  in  part,  due  to  the  excretion  of  superfluous  quantities 
of  bodies  like  skatole.    Frequent  mistakes  in  feeding  cattle 
have  been  made  by  the  use  of  excessive  quantities  of  nitro- 
genous   food,  but  it  is  not  always  practical  to   get,  on 
economic  lines,  the  exact  mixture  one  requires.    Maize  which 
contains  no  tryptophane  is  known  to  be  somewhat  binding 
and  heating  in  its  effects.    The  simple  amino  acids,  like 
aspartic  and  glutaminic  acids,  are  produced  by  the  hydrolysis 
of  proteins  in  such  large  amount  that  relatively  they  are 
not  urgently  needed.     Even  the  benzene  nucleus  seems  to  be 
f airly  easily  obtainable  either  synthetically  or  analytically. 
The   substances   constituting   the   nucleus   of    most   cells 
contains  some  of  the  purine  bases,  which  give  rise  to  uric 
acid  in  man,  but  to  allantoin  in  beasts.     There  does  not, 
therefore,  seem  to  be  the  same  risk  of  over  supply  of  purine 
bases  to  animals  that  there  is  to  man.     In  estimating  the 
feeding  value  of  foodstuffs,  it  is  not  uncommon  to  differentiate 
between  the  true  albuminoids  and  the  amides,  that  is  to 
say,   between  nitrogen  precipitated  by  lead  acetate   and 
ammonia  volatile  with  caustic  alkali  and  steam,  or  some  such 
similar  division.    Such  bodies  as  asparagine  will  only  yield 
half  their  nitrogen  by  distillation  with  caustic  alkali  and 
steam.     Such  a  division,  at  the  best,  does  not  really  answer 
the  question  we  wish  to  ask.     What  we  really  want  to  know 


182  PLANT  PRODUCTS 

is  the  relative  proportion  of  important  ring  compounds, 
like  indole,  benzene,  or  purine.  The  reason  why  the  so- 
called  amides  have  little  value  is  that  the  compounds 
which  yield  ammonia  on  hydrolysis  are  plentiful  in  the 
products  of  hydrolysis  of  the  protein  in  most  cattle  foods. 
Compounds  like  aspartic  and  glutaminic  acids  will  probably 
supply  twenty  times  as  much  nitrogen  as  substances  of 
the  tryptophane  type,  hence  the  indole  groupings  are 
comparatively  scarce,  and,  therefore,  valuable,  whilst  the 
simple  amino  acids,  like  aspartic  acid,  are  plentiful,  and, 
therefore,  not  very  valuable.  All  these  substances  are 
probably  utilized  by  the  animal,  but  those  that  are  scarce 
in  amount  are  the  ones  whose  supply  we  have  to  consider. 
Under  special  conditions  even  ammonium  acetate  has  proved 
useful  for  increasing  the  protein  laid  on  by  beasts.  Never- 
theless, no  very  practical  system  has  yet  been  discovered 
to  obtain  a  clear  idea  of  the  value  of  the  different  proteins 
in  the  foods. 

The  metabolic  changes  of  the  fats  result  in  hydrolysis, 
oxidation,  and  production  of  sugars.  The  sugars  themselves 
break  down  with  the  production  of  carbonic  acid.  The 
proteins  are  chiefly  concerned  in  the  building  up  and  repairing 
of  the  structural  part  of  the  animal  body,  the  fats  and  the 
sugars  being  chiefly  concerned  with  the  production  of 
energy. 

REFERENCES   TO   SECTION   I 

Wood  and  Yule,  "  Statistics  of  British  Feeding  Trials,  and  the  Starch 

Equivalent  Theory,"  Journ.  Agric.  Science,  vi.,  p.  233. 

Wood  and  Hill,  "  Skin  Temperature  and  Fattening  Capacity  in  Oxen," 

Journ.  Agric.  Science,  vi.,  p.  252. 

Hall,  "  Agriculture  after  the  War,"  p.  39.     (Murray.) 

Armsby,  "  The  Principles  of  Animal  Nutrition." 

Bennett,  "  Animal  Proteids."     (Bailliere,  Tindall  and  Cox.) 

Luck,  "  The  Elements  of  the  Science  of  Nutrition."     (Philadelphia.) 


SECTION  II.—  THE  FOODS  FED  TO   BEASTS 

Water  in  Foods. — All  foods  fed  to  stock  contain  a 
certain  amount  of  water  in  their  composition.  Soft  turnips 
contain  as  much  as  92  per  cent,  of  water,  mangolds  about 
86  per  cent,  of  water,  and  concentrated  foodstuffs,  like 
the  oil  cakes  and  grains,  contain  about  12  per  cent,  of  water. 
When  foods  contain  large  quantities  of  water,  little  extra 
water  is  needed  for  drinking  purposes,  but  when  consider- 
able quantities  of  dry  food  are  fed,  water  must  be  used  in 
addition.  The  consideration  of  the  water  supply  for  stock 
closely  resembles  the  study  of  the  water  supply  for  human 
consumption,  but  a  considerably  lower  standard  may  be 
adopted.  Drainage  from  fields  may  be  utilized  for  this 
purpose,  but  care  should  be  taken  that  the  water  is  not  muddy 
or  fouled  by  any  trampling  by  the  cattle  themselves.  A 
short  lead  of  underground  pipes,  conveying  the  water  from 
this  source  to  a  properly  constructed  cattle  trough,  will 
result  in  the  supply  of  a  considerably  purer  water.  The 
mere  process  of  running  through  pipes  tends  to  purify  the 
water,  as  it  comes  into  contact  with  fresh  air  in  the  course 
of  its  fall.  A  small  underground  reservoir  is  also  convenient 
to  remove  earthy  matters  in  suspension.  Where  large 
quantities  of  vegetable  growths  occur  in  the  drinking  supply, 
unsatisfactory  results  may  be  observed.  Each  pound  of 
dry  food  used  needs  seven  pounds  of  water  for  pigs,  four  or 
six  pounds  for  cows,  or  oxen,  and  two  or  three  pounds  for 
horses.  Well-fed  animals  with  a  good  coat  usually  develop 
excessive  heat,  and,  therefore,  do  not  suffer  from  drinking 
cold  water.  Pigs,  however,  being  smaller  animals,  and  being 
ill  protected  by  hair,  not  infrequently  show  some  good 
results  from  heating  the  water  supply.  When  water,  in 


184  PLANT  PRODUCTS 

combination  with  food,  is  supplied  in  excess,  an  unnecessary 
strain  is  placed  upon  the  kidneys  of  the  animals  concerned. 
Increased  metabolism  therefore  takes  place,  and  the  water 
actually  passed  has  to  be  heated  to  the  body  temperature. 
Waste  of  energy,  and  therefore  food,  is  the  result  of  supply- 
ing unnecessary  amounts  of  water.  It  is,  of  course,  not 
practical  to  cut  the  water  supply  down  below  the  figure  which 
is  necessary  for  the  health  and  comfort  of  the  beasts.  They 
themselves  will  be  the  first  to  make  objection  should  they 
be  kept  thirsty. 

The  Fat  in  Foods. — The  foods  fed  to  beasts  generally 
contain  fat  in  small  quantities.  The  common  analytical 
figures,  which  represent  the  total  amount  of  material 
extracted  from  the  food  by  the  use  of  ether,  include  other 
substances  than  true  oils  and  fats.  Anything  in  the  nature 
of  wax  or  resin  will  also  be  extracted  by  ether.  In  the  case 
of  the  oil  seeds,  the  proportion  of  waxes  and  resins  is  relatively 
small,  but  in  such  food  materials  as  hay,  the  proportion 
of  ether  extract  which  is  not  true  fat  is  very  considerable, 
and  may  amount  to  one-half.  In  such  cases,  however,  the 
total  percentage  of  oil  is  too  small  to  make  much  difference, 
whether  it  is  considered  or  not  in  calculating  rations.  The 
true  fats  are  glycerine  esters  of  some  of  the  fatty  acids  (see 
p.  108).  When  fed  to  stock,  the  fat  undergoes  hydrolysis 
in  the  process  of  digestion  with  the  production  of  the 
corresponding  fatty  acids  and  glycerine,  which  are  absorbed 
and  built  up  into  the  fatty  tissues  of  the  animal  body. 
Considerable  portions  of  the  breaking-down  products  of 
the  fats  will  be  oxidized,  for  the  purpose  of  producing  heat, 
in  consequence  of  which  the  properties  of  the  fat  laid  on 
by  the  animal  are  more  dependent  upon  the  animal  con- 
suming the  food  than  on  the  properties  of  the  fat  in  the  food 
consumed:  For  rough  purposes,  the  food  value  of  fats  is 
about  2j  times  the  value  of  the  same  weight  of  carbo- 
hydrates. 

The  Nitrogenous  Matter  in  Food.  — The  proteins  in  the 
foods  are  similar  to  those  described  in  Part  III.,  p.  147. 
So  far  as  regards  the  more  concentrated  foods,  the  total 


THE   FOODS  FED   TO  BEASTS  185 

nitrogen  multiplied  by  6  J  is  a  good  enough  approximation,  but 
in  some  of  the  less  concentrated  foods,  like  hay  and  turnips, 
it  has  been  found  in  practice  that  some  further  information 
is  desirable.  For  this  reason  the  nitrogenous  matter  is 
commonly  divided  into  the  two  groups  of  the  "  true  albumi- 
noids "  and  the  "amides"  (see  p.  147).  The  particular 
amino  acids  required  by  the  beasts  will  vary  according  to 
the  needs  of  the  animal,  which  will  depend  partly  upon  the 
species,  partly  upon  the  age,  and  partly  upon  the  condition 
of  health.  Foods  may  not  infrequently  contain  a  few  special 
nitrogenous  matters,  such  as  some  of  the  nitrogenous  gluco- 
sides.  Some  of  these,  of  which  amygdalin  and  linimarin 
may  be  taken  as  types,  evolve  prussic  acid  under  certain  con- 
ditions (see  p.  137).  Potatoes  contain  another  special  nitro- 
genous glucoside  called  solanin.  Potato  eyes  may  contain 
large  quantities,  even  up  to  5  per  cent.,  but  the  haulms  do 
not  usually  contain  more  than  about  0*03  per  cent.  This 
substance  is  slightly  poisonous,  but  the  amount  present  is 
usually  too  small  to  produce  any  serious  effect.  Special 
foods  may  sometimes  contain  nitrates,  especially  crops  grown 
under  droughty  conditions.  Probably  the  nitrates  them- 
selves are  not  very  harmful,  but  they  usually  accompany  other 
forms  of  nitrogen,  neither  protein  nor  amide,  and  injurious 
results  have  been  observed  under  these  conditions.  Man- 
golds, for  example,  are  not  satisfactory  to  feed  immediately 
after  pulling,  but  after  an  interval  of  storage  they  become 
riper,  the  nitrates,  among  other  changes,  being  converted 
into  organic  nitrogen  bodies,  and  the  irritating  compounds 
being  built  up  into  proteins.  In  India,  juari  and  other 
fodders  when  cut  unripe  in  droughts  act  in  a  similar 
manner.  In  sound  food  the  nitrogen  in  the  forms  of  true 
albuminoids  and  amides  (see  p.  181)  usually  adds  up  to  the 
total  nitrogen,  but  in  unripe  root  crops  and  leaves  there 
are  often  other  forms  of  nitrogen  than  these.  A  portion 
of  the  other  forms  will  often  be  nitrates,  but  there  are  other 
nitrogenous  compounds  whose  constitution  is  little  under- 
stood. For  a  large  number  of  purposes  no  effort  is  made  to 
do  more  than  determine  the  total  nitrogen  in  the  foodstuffs. 


186  PLANT  PRODUCTS 

It  is  only  in  the  case  of  the  root  crops  and  hay  that  any 
serious  error  would  be  introduced  by  neglecting  to  measure 
the  amides  separately. 

The  Carbohydrates. — Sugar  is  much  appreciated  by 
stock,  as  it  gives  a  considerable  flavour  to  the  food,  and  is 
often  valuable  to  the  farmer  by  inducing  stock  to  eat  other- 
wise not  very  palatable  articles.    The  sugars  found  in  cattle 
foods  are  cane  sugar  and  glucose.     Whilst  these  materials 
are    much  appreciated  by  stock,   experimental    evidence 
shows  that  their  body- building  power  is  lower  than  that 
of  the  starches,  but  as  such  experimental  results  can  only 
be  obtained  by  feeding  sugar    in   large    quantities,  it  is 
probable  that  they  do  not  reflect  the  conditions  of  ordinary 
farm  practice.     Sugar,   being  instantly  soluble   in  water, 
will  enter  the  blood  stream,  and  pass  through  the  liver  at 
a  great  rate.     Very  small  quantities  of  sugar  will  not  throw 
any  strain  upon  the  liver.     It  is,  therefore,  to  be  expected 
that  the  food  value  of  sugar  will  depend  largely  upon  the 
amounts  fed,  and  that,  whilst  it  may  have  a  high  value  when 
the  quantity  is  small,  it  may  have  a  low  value  when  the 
quantity  is  large.     In  practice,  owing  to  the  expense,  large 
quantities  of  sugar  are  probably  not  fed.     In  the  case  of 
stock  consuming  large  quantities  of  swedes,  the  total  amount 
of  sugar  fed  is  very  considerable.     Swedes  contain  more  than 
one-half  of  their  total  solid  material  in  the  form  of  sugar, 
and  if  these  constitute  half  of  the  dry  matter  fed,  it  would 
mean  that  25  per  cent,  of  the  ration  was  sugar.     Experience 
shows  that  this  is  not  economical,  the  inefficiency  of  heavy 
root  feeding  being  generally  attributed  to  the  water  being 
in  excess,  but  it  may  partly  be  due  to  the  sugar  also  being 
in  excess.     Sugar  which  is  consumed  by  beasts  in  the  form 
of  swede  turnips  would  not  be  digested  at  the   same  rate 
as  sugar  in  the  form  of  treacle,  and,  therefore,  the  strain 
upon  the  liver  would  not  be  so  marked.     Possibly  this  in 
the  explanation  why  feeding  sugar  in  the  form  of  roots 
appears  to  be  more  satisfactory  than  feeding  it  in  the  more 
concentrated  form. 

Starch. — In  the  case  of  feeding  animals  there  does  not 


THE   FOODS   FED    TO   BEASTS  187 

seem  to  be  any  advantage  in  boiling  starch,  the  digestibilities 
appearing  about  the  same  in  boiled  and  unboiled  starches. 
The  starch  is  converted  during  the  process  of  digestion  into 
glucose,  and  this  passes  through  the  liver,  where  it  may  be 
temporarily  deposited  as  glycogen.  Starch  is  particularly 
liable  to  bacterial  decomposition  in  the  intestines,  probably 
due  to  the  fact  that  its  digestion  is  somewhat  slow.  Starch 
may,  therefore,  very  easily  suffer  considerable  loss. 

Pectins,  Mucilage,  etc.  — This  group  of  carbohydrates 
for  the  most  part  resembles  starch,  but  sometimes  contains 
a  proportion  of  pentosans.  The  general  feeding  value  of  the 
carbohydrates  is  the  same  as  that  of  starch.  Under  digestive 
conditions  these  change  into  glucose,  though  some  pentose  is 
also  formed. 

The  Fibrous  Materials  in  Foods.— The  portion 
of  the  food  material  which  is  not  soluble  in  ether,  dilute 
sulphuric  acid,  and  dilute  potash  is  considered  the  indigestible 
fibre.  This  material  is  composed  largely  of  cellulose, 
together  with  lignin,  and  other  materials.  The  ordinary 
analytical  processes  rather  resemble  an  attempt  to  give  a 
rough  imitation  of  digestion  than  any  effort  to  obtain  a 
definite  chemical  subdivision.  The  common  method  of 
analysis  will  give  very  valuable  figures  representing  the 
indigestible  material,  and  is  quite  a  fair  approximation  of 
the  actual  digestive  process  of  the  animal.  Up  to  a  certain 
point  the  ruminants  require  fibre  in  their  food,  as  their 
digestive  processes  are  adjusted  to  foods  of  this  type,  and 
if  fibrous  materials  are  withheld,  the  digestion  is  interfered 
with.  Within  limitations,  therefore,  fibre  possesses  a  real 
value,  but  it  is  not  common  to  consider  this  fact,  because 
the  fibrous  foodstuffs  are  relatively  cheap,  and,  therefore, 
the  tendency  is  to  feed  rather  more  fibre  than  is  absolutely 
necessary,  but  this  consideration  would  not  apply  to  a 
town  cowkeeper,  who  has  to  purchase  everything  in  the  way 
of  food,  as  it  does  to  a  farmer  who  grows  his  own  hay.  In 
small  quantities,  therefore,  one  must  regard  fibre  as  being 
useful.  In  large  quantities  it  is  not  merely  useless  but 
highly  objectionable. 


i88  PLANT  PRODUCTS 

Digestion.  — Attempts  have  been  made  to  measure  the 
ultimate  results  of  the  digestive  processes  in  animals.  In 
such  experiments  all  the  food  consumed  by  the  animal  is 
analysed,  and,  in  addition,  all  the  solid  excreta  are  analysed 
in  the  same  way.  The  difference  between  the  two  is  supposed 
to  represent  the  material  which  has  been  digested.  There 
are  several  errors,  nevertheless,  in  this  assumption.  In  the 
process  of  digestion,  portions  of  the  food  are  first  absorbed, 
converted  into  intestinal  mucus,  etc.,  and  are  excreted. 
The  ultimate  gain  to  the  animal  is  quite  correctly  represented 
by  the  difference  between  the  two  analyses  named  above, 
but  a  more  serious  error  is  introduced  by  bacterial  activity. 
The  bacteria  are,  all  the  time  digestion  is  going  on,  struggling 
to  get  a  share  of  the  food.  Such  bacteria  as  oxidize  the  food 
materials  will  produce  just  the  same  amount  of  heat  as 
the  oxidation  would  give  under  other  circumstances.  If 
the  animal  requires  this  heat  there  would  be  no  loss.  If  the 
animal  does  not  require  the  heat,  as  might  be  the  case  in 
hot  weather,  then  the  heat  produced  is  not  merely  useless, 
but  a  nuisance.  The  bacteria,  however,  that  flourish  in 
the  intestinal  tracts,  are  for  the  most  part  of  a  different  type, 
and  much  of  their  energy  is  devoted  to  the  decomposition 
of  carbohydrates  with  the  production  of  marsh  gas  and 
carbon  dioxide.  As  much  as  700  litres  of  marsh  gas  from 
one  beast  in  one  day  has  been  observed,  which  is  equivalent 
to  a  waste  of  four  pounds  of  carbohydrate.  These  carbo- 
hydrates, of  course,  disappear,  and  are  considered  as  digested, 
although  they  have  produced  little  heat,  and  no  good  of 
any  kind  to  the  animal.  Such  fermentive  changes  depend 
upon  slow  digestion,  the  quicker  the  animal  can  digest  the 
food  the  smaller  is  the  share  available  for  the  bacteria. 
As  the  result  of  such  experiments,  tables  of  digestibilities 
have  been  constructed  (see  Kellner).  Such  tables  will 
allow  one  to  calculate  the  probable  amount  of  food  actually 
digested  by  the  beasts  from  any  particular  food  supplied. 
The  ordinary  analysis  can  be  carried  out  according  to  the 
text-books  (see  Bibliography),  and  then  the  digestive 
coefficients  used  to  convert  these  figures  into  digestibilities. 


THE   FOODS   FED   TO  BEASTS  189 

Such  a  calculation  assumes  that  the  figures  apply  to  the 
particular  case  in  question.  The  full  table  given  in  Kellner's 
work  supplies  a  considerable  amount  of  information  which 
permits  one  to  apply  these  values  with  a  fair  degree  of 
certainty.  There  is,  however,  always  the  difference  between 
the  actual  conditions  prevailing  and  those  under  which  the 
tables  were  deduced.  A  study  of  the  tables  in  Kellner's 
work  shows  that  in  some  cases  very  wide  variations  in  the 
results  were  obtained.  The  variations  compensate  for  one 
another  to  some  slight  extent .  Probably  the  great  variations 
that  may  be  observed  in  the  digestible  fibre  are  really 
attributable  to  the  fact  that  some  of  the  materials  which 
are  possibly  called  "  fibre  "  in  the  solid  excreta  of  the  beasts 
are  really  bacterial  residues.  The  fluctuations  observable 
in  the  column  "  total  matter  digested  "  are  more  valuable 
in  assessing  the  probable  error  in  these  experiments .  A  study 
of  the  tables  will  convince  one  that  the  use  of  these  tables 
will  give  a  figure  for  the  digestible  ingredient  per  cent,  which 
is  true  to  two  or  three  units,  but  cannot  be  considered  as 
being  any  closer  than  that.  In  some  instances  it  is  quite 
obvious  that  Kellner  himself  recognized  that  the  figures  of  a 
few  experiments  are  not  very  reliable.  It  will  be  noted,  on 
referring  to  p.  388,  that  Kellner  gives  digestible  coefficients 
for  "palm  nut  cake"  and  "palm  nut  meal,  extracted/' 
which  differ  from  one  another  to  a  degree  which  is  difficult 
to  credit ;  but  when  he  makes  use  of  these  figures  for  compiling 
the  table  on  p.  377,  he  uses  for  calculating  the  digestible 
nutrients  in  those  two  substances,  not  the  figures  he  has 
himself  quoted,  but  the  average  of  the  two  cases.  That  is  to 
say,  in  calculating  the  digestibility  of  palm  nut  cake,  he 
does  not  use  his  own  figures  but  an  average  obtained  from 
palm  nut  cake  and  palm  nut  meal.  This  procedure  is  quite 
legitimate,  of  course,  but  shows  that  Kellner  did  not  himself 
attribute  to  his  own  work  that  degree  of  precision  which  is 
sometimes  assumed  by  those  who  use  his  tables.  Such 
apparent  discrepancies  in  the  table  of  digestibility  of  decorti- 
cated cotton  seed  meal,  where  the  digestibility  coefficient 
of  the  fibre  varies  from  o  to  100,  though  appearing  very  big, 


igo  PLANT  PRODUCTS 

are  not  of  great  importance,  because  the  percentage  of  crude 
fibre  in  this  meal  is  very  small.  The  fluctuations  in  the 
digestibility  of  the  crude  fibre  in  undecorticated  cotton  cake, 
which  vary  from  2  to  24  per  cent.,  although  superficially 
not  so  serious,  are  in  practice  of  more  importance,  since 
the  percentage  of  fibre  in  this  food  is  about  20  per  cent. 
In  spite,  however,  of  these  apparently  large  discrepancies, 
experience  has  shown  that  feeding  standards  which  are 
based  ultimately  on  these  experiments  are  practically 
sound. 

During  digestion,  the  lining  of  the  stomach  itself  is 
protected  by  a  supply  of  anti-pepsin,  which  is  produced 
for  this  purpose.  If  an  animal  were  to  die  suddenly  during 
the  process  of  digestion,  the  supply  of  this  anti-pepsin  would 
fail  along  with  the  rest  of  the  circulation,  and  the  lining  of 
the  stomach  would  be  partly  digested  by  the  digestive 
juices.  Some  portion  of  the  materials  which  are  considered 
as  not  having  been  digested  are  really  bacterial  remains, 
which,  of  course,  have  been  produced  from  the  food  by  the 
life  of  bacteria,  and  have  done  no  good  to  the  animal. 

REFERENCES   TO   SECTION    II 

Wanklyn,  "  Water  Analysis."     (Kegan  Paul.) 
Evans,  "Driage,"  Agric.  Journ.  India,  1917,  p.  234. 
Leathes,  "  The  Fats.     Monograph  on  Biochemistry."     (Longmans.) 
Collins,  "  The  Feeding  of  Linseed  to  Calves,"  Journ.  Board  of  Agricul- 
ture, 1915-16,  p.  120. 

Bainbridge,  Collins,  and  Menzies,  "  Experiments  on  the  Kidneys  of  the 
Frog,"  Proc.  Roy.  Soc.,  B.,  vol.  86,  1013. 

Plimmer,  "  The  Chemical  Constitution  of  the  Proteins.   Monograph  of 
Biochemistry.     (Longmans . ) 

Armstrong,  "  The  Simple  Carbohydrates."     (Longmans.) 
A.  Rendall  Short,  "  The  New  Physiology,"  p.  84.     (Simpkin.) 
Kellner,  "  The  Scientific  Feeding  of  Animals,"  p.  379.     (Duckworth.) 
Warington,  "  Chemistry  of  the  Farm,"  p.  144.     (Vinton.) 


SECTION  IIL-CALORIFIC  VALUE   OF   FOODS 

The  Animal  as  a  Heat  Engine. — Just  as  an  engine  may 
be  regarded  as  a  means  of  converting  the  fuel  supplied  into 
work  done,  so  a  food  fed  to  a  horse  may  be  also  regarded  in  the 
same  light,  and  the  food  fed  to  a  milk-producing  or  fattening 
beast  may  be  also  regarded  from  the  energy  point  of  view. 
Energy  is  usually  represented  in  terms  of  calories.  The 
calorie  adopted  in  theoretical  considerations  is  the  amount  of 
heat  necessary  to  raise  the  temperature  of  one  gramme  of 
water  one  degree  Centigrade.  In  practical,  big-scale  work  it 
is  preferable  to  employ  a  unit  1000  times  that  size,  and  to 
define  this  large  Calorie  as  the  amount  of  heat  required  to 
raise  the  temperature  of  i  kilogramme  of  water  i°  Cent.  On 
such  a  scale,  the  complete  combustion  of  earth  nut  oil 
would  give  8'8  Calories,  wheat  gluten  5*8  Calories,  starch 
4- 1  Calories,  and  urea  2-5  Calories.  In  the  animal  body  the 
final  products  of  the  decomposition  of  the  foods  differ  from 
those  obtained  in  the  steel  bomb  used  for  determining  heat 
equivalents,  owing  to  the  fact  that  the  nitrogen  is  not  given 
off  as  elementary  nitrogen,  but  is  given  off  in  the  form  of 
urea.  As  the  amount  of  nitrogen  in  urea  is  nearly  three 
times  as  great  as  that  in  the  ordinary  albuminoid  or  protein, 
one  part  of  protein  may  be  assumed  to  produce  one-third 
of  a  part  of  urea,  giving  a  loss  of  2  -5-7-3  Calories,  and, 
therefore,  the  5-8  Calories  from  wheat  gluten  would  only 
produce  about  5  Calories  in  the  animal  body,  because  the 
fractional  part  would  represent  the  loss  due  to  producing 
urea  instead  of  nitrogen.  No  such  deduction,  of  course, 
has  to  be  made  for  the  carbohydrates  or  oils.  The  calories 
evolved  in  the  consumption  of  a  food,  therefore,  needs 
two  deductions  to  be  made  from  them.  Firstly  the 


PLANT  PRODUCTS 

deduction  for  indigestible  material  (see  p.  188),  and 
secondly,  the  deduction  due  to  the  urea  produced  in 
place  of  nitrogen.  Further,  during  the  process  of  diges- 
tion, bacterial  fermentation  produces  considerable  loss,  and 
further  there  is  a  loss  of  energy  in  production,  due  to 
such  operations  as  chewing  tough  fibres,  intestinal  move- 
ment, circulation  of  the  blood,  the  action  of  the  lungs, 
etc.  It  is,  however,  possible  to  prepare  a  balance-sheet  of 
income  and  expenditure  in  terms  of  calories.  The  following 
represents  the  result  of  a  particular  experiment  on  a  well- 
fed  ox : — 

TABLE  24. 


Income. 

Expenditure. 

Calories. 

Calories. 

Food         .  .         .  .          .  .     52,929 

Faeces 

I5»9i6 

Urine 

1,686 

Marsh  gas 

3,383 

Maintenance  (othe 

exper 

- 

ments)     .  . 

17,320 

Flesh 

246 

Fat  .. 

8,069 

Energy  for  fattening 

6,309 

52,929 

As  regards  the  internal  work  in  the  animal,  if  the  heat 
produced  is  really  required  there  will  be  no  loss  due  to  the 
food  itself ;  but  if  the  heat  produced  by  this  work  is  not 
necessary,  then  such  energy  will  have  to  be  considered  in 
the  above  table  under  the  head  of  the  extra  energy  for  fatten- 
ing processes.  The  conditions  are  much  the  same  as  those 
prevailing  in  a  steam  engine.  A  locomotive  "  standing  in 
steam  "  is  roughly  reckoned  to  consume  half  as  much  coal 
as  if  it  were  really  working,  and  similarly,  the  animal  takes 
a  good  deal  of  food  for  mere  maintenance,  as  is  exhibited  in 
the  table  given  above.  If  an  animal  is  fed  with  more  food 
than  is  necessary  for  mere  maintenance,  a  portion  of  the  food 
will  be  used  for  the  production  of  flesh  and  fat,  but  the  putting 
on  of  this  flesh  and  fat  will  involve  a  certain  consumption 


CALORIFIC    VALUE  OF  FOODS  193 

of  food,  just  in  the  same  way  as  a  steam  engine  will  require 
a  certain  amount  of  coal  to  keep  up  the  steam  pressure, 
though  doing  no  work,  and  any  work  required  from  it  would 
necessitate  a  further  allowance  of  coal,  a  portion  only  of 
which  would  be  accounted  for  in  the  work  done.  The  amount 
of  energy  required  for  the  utilization  of  food  materials  depends 
upon  the  way  in  which  the  food  materials  are  presented 
to  the  animal.  Pure  foods  and  sugars  can  be  digested  with 
the  least  exertion,  but  when  these  substances  occur  in  food 
among  hay  or  straw,  then  the  animal  will  have  to  do  much 
chewing,  and  other  work,  before  the  fats,  carbohydrates, 
and  proteins  are  acted  on  by  the  enzymes  in  the  digestive 
tracts.  Moreover,  a  far  larger  quantity  of  enzyme  will  have 
to  be  produced,  because  a  great  many  enzymes  are  condensed 
on  the  surface  of  the  fibrous  matter  in  the  alimentary  tract, 
an4  most  rates  of  decomposition  depending  upon  enzymes  are 
considerably  retarded  by  the  presence  of  cellulose  in  the 
digestive  tracts ;  bulky  food  will  also  need  a  greater  amount 
of  fluid,  which  has  to  be  produced  by  the  animal,  at  some 
expenditure  of  energy.  Under  very  extreme  circumstances, 
energy  expended  in  the  effort  to  digest  food  may  exceed 
the  energy  obtained  from  the  digested  part  of  the  food. 
Ruminants  swallow  much  of  their  food  with  only  partial 
mastication  but  regurgitate  it,  "  chew  the  cud,"  and 
again  swallow.  The  finely  comminated  material  is  filtered 
out  by  the  third  stomach  and  the  insufficiently  chewed  fibres 
again  regurgitated.  In  this  way  a  ruminant  can  make  much 
more  effective  use  of  fibrous  food  than  a  non-ruminant 
herbivorous  animal.  A  horse  is  quite  incapable  of  living  upon 
straw  alone,  although  an  ox  may  just  manage  to  keep  itself 
alive.  If,  however,  part  of  the  work  of  digestion  be  done 
beforehand,  much  better  results  can  be  obtained.  Kellner 
found  that  straw  pulp,  as  used  for  papermaking,  was  far  more 
digestible  than  straw  itself.  Of  the  straw  pulp  as  much  as 
88  per  cent,  could  be  digested  by  an  ox,  and,  after  allowing 
for  the  work  of  digestion,  the  straw  pulp  was  worth  rather 
more  than  one-half  its  weight  of  starch  as  a  food  material. 
As,  however,  in  the  process  of  turning  straw  into  paper  pulp, 
D,  13 


194  PLANT  PRODUCTS 

about  one-half  the  weight  is  removed,  the  ultimate  advantage 
of  such  treatment  is  not  very  marked,  although  it  does 
undoubtedly  show  that  if  the  ox  is  assisted  in  his  digestive 
process,  a  larger  amount  of  energy  will  be  left  for  him  to 
make  some  good  use  of.  In  a  similar  way,  merely  chaffing 
straw  or  hay  reduces  the  work  necessary  to  be  done  by  the 
beasts,  and,  therefore,  a  higher  feeding  value  can  be  obtained. 
When  animals  are  merely  maintained  in  store  condition 
the  amount  of  food  necessary  to  keep  them  is  small,  and  may 
be  of  a  coarse  quality,  since  the  energy  expended  in  chewing 
is  useful  for  maintaining  the  temperature.  If,  however, 
animals  are  called  upon  for  a  big  output  of  energy,  they  must 
be  fed  on  foods  which  do  not  involve  so  much  internal 
expenditure.  A  horse  that  is  doing  nothing  can  live  upon 
hay  and  grass,  but  the  harder  the  work  given,  the  greater 
must  be  the  proportion  of  concentrated  foods.  If  the  external 
work  is  to  be  increased,  the  internal  work  must  be  decreased. 
The  same  remark  applies  to  cattle  and  sheep.  The  relation- 
ship between  the  amount  of  calories  necessary  for  maintenance 
and  the  live  weight  is  not  constant,  but  depends  upon  the 
size  of  the  beast.  Roughly  speaking,  the  loss  of  heat  from 
an  animal  body  is  proportionate  to  the  surface,  though  the 
amount  of  hair  and  fur  will  effect  this  considerably.  The 
theory,  however,  that  the  amount  of  heat  is  proportionate  to 
the  surface  is  surprisingly  close  to  what  is  obtained  in  practice, 
although  it  is  very  easy  to  push  the  theory  too  far.  If 
the  "  surface  law  "  is  considered,  it  will  be  seen  that  the 
weight  of  a  beast  will  vary  as  the  cube  of  the  length,  whilst 
the  surface  will  vary  as  the  square  of  the  length.  Hence,  a 
small  increment  in  the  weight  of  the  beast  corresponds  with 
two-thirds  of  that  small  increment  in  the  food.1 

But  as  a  beast  grows  older  its  digestion  diminishes,  and 
more  food  has  to  be  fed  to  counteract  the  decrease  in 
digested  nutriments,  hence  the  common  rule  of  reckoning 

1   Since  w  *>l3,  /eosoo/*eo  wl 

where  w=weight,  /= length,  /=  food,  s=surface. 


CALORIFIC   VALUE  OF  FOODS  195 

the  food  as  proportionate  to  the  live  weight  is  not  so  very 
far  out  in  practice.  The  surface  law  is  more  useful  in  com- 
paring dissimilar  animals  at  the  same  period  of  growth  than 
of  similar  animals  at  different  periods  of  growth.  The  surface 
law  enables  one  to  equate  the  rations  of  a  guinea  pig  and  a 
galloway,  both  three-quarters  grown,  but  does  not  enable  one 
to  equate  the  rations  of  a  calf  and  a  Christmas  fat  beast. 

An  ox  weighing  1200  Ibs.  needs  12,000  Calories  per 
diem  for  its  maintenance,  whilst  a  sheep  weighing  about  100 
Ibs.  requires  2000  Calories.  Directly  any  work  or  fattening 
is  needed,  the  amount  of  food  must  be  increased.  A  horse 
weighing  1125  Ibs.  required  for  maintenance  12,600  Calories, 
but  when  doing  fairly  heavy  work,  required  more  than 
double  that  quantity  for  its  output  of  energy. 

Many  different  systems  have  arisen  to  use  the  purely 
theoretical  considerations  given  above,  and  apply  them  to 
the  practical  rule- of -thumb  methods  of  feeding  commonly 
adopted.  These  systems  have  followed  the  needs  of  the 
day.  At  the  time  when  purchased  cattle  foods  came  into 
common  use  there  was  much  more  corn  grown  than  at  present. 
Much  of  this  corn  was  grown  on  poor  land,  insufficiently 
manured,  with  a  correspondingly  big  proportion  of  tail  corn, 
or  with  entire  crops  unsuited  for  the  production  of  bread. 
The  beasts,  therefore,  received  plenty  of  carbohydrates 
in  corn  and  straw  whilst  the  albuminoids  were  supplied  by 
good  hay,  but  the  oil  was  very  deficient.  Hence  the  "  oil 
theory  "  of  the  day.  lyater,  as  wheat  was  grown  less  and 
less,  and  as  the  land  fell  back  to  grass  of  little  fattening 
value,  the  general  feeding  of  the  cows  became  low  in  albumi- 
noids, but  the  increasing  use  of  oil  cakes  removed  the  oil 
shortage,  and  the  "  oil  theory "  dropped  out,  and  the 
"  albuminoid  theory  "  came  in.  Of  recent  years  we  have 
had  a  dearth  of  carbohydrates,  and  the  weak  link  in  the 
chain  has  occurred  at  that  point.  But  carbohydrates  are 
too  indefinite,  being  only  a  "  difference  figure,"  hence  the 
present  use  of  the  "  starch  equivalent "  theory. 

Practical  if  rough  ratios  were  studied  in  early  research  in 
Agriculture*    I^awes  and  Gilbert,  at  Rothamsted,  deduced 


196  PLANT  PRODUCTS 

the    general  principles    that    to    obtain    one    pound    live 
weight   increase   in  the  weight  of   oxen,  thirteen  pounds 
of   dry  food   material   were  necessary,  whilst  about  nine 
pounds  of  dry  food  sufficed  in  the   case   of  sheep,   and 
five  pounds  in  the  case  of  pigs,   the  foods  fed  being  of 
a  mixed  kind  common  to  the  diet  used  in  most  parts  of 
England.    The  rate  of  increase  of  an  animal  is,  however, 
much    greater    in   proportion    to    its    food    in   the    early 
stages  of  its  growth.     Some  of  the  early  experiments   of 
Lawes  and  Gilbert  on  pigs  are  convenient  evidence  on  this 
point.     In  the  first  month  they  found  that  four  pounds  of 
food  produced  an  increase  of  one  pound,  and  in  the  second 
month  it  took  five  pounds,  and  in  the  last  month  of  fattening 
it  took  as  much  as  six  and  a  quarter  pounds  to  produce  this 
increase.    There    is    here    no    resemblance    between    the 
objects  in  fattening  and  the  objects  in  obtaining  work, 
since  a  young  horse  is  not  capable  of  putting  forth  much 
energy  in  return  for  its  food,  being  occupied  chiefly  in  growing. 
One  method  of  attempting  the  assessment  of  foods  is  to 
merely  take  the  dry  matter,  which  is  an  advance  on  the 
crude  methods  commonly  adopted.     The  next  advance  on 
that  is  to  deduct  the  fibre  or  indigestible  matter.     A  further 
advance  is  to  utilize  the  complicated  tables  given  by  Kellner, 
and  a  further  method  is  to  deduce  Kellner's  starch  equivalent 
or  Hanson's  milk  unit.     Another  system  consists  of  having 
standard  rations,  tabulated  for  all  kinds  of  stock,  giving  so 
much  digestible  oil  and  carbohydrates.    The  latter  method 
has  the  objection  that  it  requires  rather  complicated  sets 
of  tables,  but  is  perhaps  the  most  comprehensible  to  the 
ordinary  practical  feeder,  who  finds  starch  equivalents  rather 
a  little  beyond  him.     At  the  present  time  the  knowledge  of 
feeding  is  not  sufficiently  advanced  to  reduce  the  question 
of  feeding  to  a  scientific  basis,  and  probably  all  these  systems 
will  remain  in  vogue.    The  difference  between  individual 
animals  is  always  very  great,  and  individuality  must  be 
allowed  for,  and  hence  great  precision  on  the  theoretical 
side  is  not  of  first-rate  importance.     In  many  instances,  a 
study  of  Kellner 'stables  will  show  what  big  variations  occur, 


CALORIFIC   VALUE  OF  FOODS  197 

even  under  carefully  controlled  experimental  conditions. 
Where  a  large  portion  of  the  food  consists  of  hay,  large 
variations  in  digestion  must  be  expected.  Kellner  found, 
for  example,  in  meadow  hay,  that  the  digestibility  varied 
from  46  to  79  per  cent.  The  digestibility  varies  roughly 
with  the  fibre,  and  the  relative  food  values  can  be  obtained 
by  the  formula,  2\  X  oil  per  cent.  -f-  albuminoids  per  cent. 
4-  carbohydrates  per  cent.  —  J  fibre  per  cent.  Kellner 's 
tables,  however,  are  the  best  available  method. 

The  most  efficient  animals  for  converting  cattle  food  into 
human  food  are  undoubtedly  those  producing  milk.  The 
daily  ration  for  a  fattening  beast  is  very  similar  to  that  for 
a  cow  giving  about  two  gallons  of  milk  a  day.  In  a  week  a 
fattening  beast  would  give  perhaps  about  n  Ibs.  of  beef,  as 
against  140  Ibs.  of  milk  from  a  cow.  As  the  food  value  of 
the  beef  is  about  double  that  of  the  milk,  weight  for  weight, 
the  advantage  of  milk  is  seen  to  be  enormous.  Even  if  the 
milk  is  converted  into  cheese,  about  14  Ibs.  of  cheese  would 
be  obtained,  and  again,  cheese  is  more  than  double  the  feeding 
value  of  beef,  weight  for  weight,  so  that  under  any  circum- 
stances the  cow  is  far  more  efficient  than  the  bullock  for 
converting  cattle  food  into  human  food.  Of  course,  the 
amount  of  labour  involved  with  dairy  stock  is  greater  than 
that  of  fattening  stock.  The  next  most  efficient  animal  to 
the  cow  is  probably  the  pig,  and  sheep  are  generally  rather 
better  than  the  ox  for  the  utilization  of  food  material, 
though  mixed  grazing  is  best.  On  the  general  average, 
the  sheep  get  lower  quality  food,  and  give  a  better  return. 
If,  however,  cattle  were  slaughtered  early,  for  the  production 
of  much  more  veal  and  less  beef,  economy  would  be  effected 
in  this  way ;  but,  on  the  other  hand,  the  earlier  slaughtered 
animals  will  need  to  be  fed  with  an  average  higher  quality 
food,  and  an  average  greater  expenditure  of  labour.  Poultry 
are  not  economical  converters  of  low-grade  food  into  human 
food.  It  is  only  if  they  are  fed  to  a  large  extent  on  such 
things  as  clover  meal  and  fish  meal  that  they  can  be  considered 
as  producing  human  food  economically.  Tables  25  and  26 
give  the  data  necessary  to  convert  calories  into  human 


igS 


PLANT  PRODUCTS 


feeding  equivalents.  The  figures  in  Table  25  refer  to  a  man 
at  ease,  in  temperate  climates.  A  man  at  perfect  rest, 
lying  in  bed,  would  only  need  about  2000  Calories  a  day ; 
with  eight  hours'  hard  work,  3250  Calories  (Table  26) ;  with 
very  hard  work,  not  actually  detrimental  to  health,  3830 
Calories. 

TABLE  25. — HUMAN  HEAT  ACCOUNT.     AT  EASE. 


Calories 
per  diem. 

Radiation  (ordinary  clothing) 
Evaporation  of  water  from  skin  and  lungs 
Heating  respired  air 
Heating  food  and  water  to  body  temperature 
Working  of  heart,  etc.          .  . 

1536 
611 
80 
53 
150 

Total 


2430 


TABLE  26. — DAILY  HUMAN  RATIONS  FOR  EIGHT  HOUBS' 
HARD  WORK. 


Total. 

Digestible. 

Protein 
Fats        
Carbohydrates 

gm. 
100 
100 

500 

gm. 
92 
95 
485 

Calories. 

377 
883 
1988 

3248 

One  hundred  head  of  population,  consisting  of  mixed 
men,  women,  and  children,  may  be  considered  as  equal  to 
seventy-seven  men.  One  "  person  "  needs  a  million  Calories 
per  annum. 


REFERENCES   TO   SECTION  III 

Maidment,  "  The  Home  Dairy,"  pp.  15,  23.     (Simpkin,  Marshall.) 
Wright,  "  The  Composition  and  Nutritive  Value  of  Mutton  and  Lamb," 

Journ.  Soc.  Chem.  Ind.,  1916,  p.  234. 

"  Comparative  Values  of  Feeding  Stuffs,"  Journ.  Board  of  Agriculture, 

1915-16,  p.  53. 

James  Long,  "  Food  and  Fitness."     (Chapman  and  Hall.) 

Crowther,  "The  Feeding  of  Farm  Stock,"  Journ.  Board  of  Agriculture, 

1912-13,  p.  107. 


SECTION  IV.— DAIRY   PRODUCTS 

Mn,K  is  composed  of  about  87  per  cent,  water,  about 
3*8  per  cent,  of  fat,  and  9*0  per  cent,  of  other  solids.  The 
fat  resembles  ordinary  animal  fat,  excepting  that  it  con- 
tains rather  higher  proportions  of  butyrin  and  other  fats 
containing  the  lower  fatty  acids.  The  chief  nitrogenous 
material  is  casein,  or  caseinogen,  which  is  characterized 
by  being  precipitated  in  acid  solutions.  Milk  also  con- 
tains a  small  quantity  of  albumen,  which  is  precipitable 
by  heat.  Milk  sugar  is  the  only  form  of  sugar  present 
in  milk,  and  on  hydrolysis  or  digestion  gives  glucose 
and  galactose.  The  mineral  matter  is  fairly  constant  at 
°*75  Per  cent,  of  which  calcium  phosphate,  sodium  chloride, 
and  potassium  chloride  constitute  the  major  part.  Milk 
is  produced  directly  by  the  breaking-down  process  of  the 
tissues  in  the  glands,  and  is  not  dependent  upon  the  composi- 
tion of  the  food  supplied,  but  is  maintained  in  molecular 
equilibrium  with  the  blood.  Consequently,  the  molecular 
concentration  of  the  soluble  portions  is  fairly  constant, 
but  a  deficiency  of  milk  sugar  may  be  replaced  by  an  increase 
in  the  amount  of  soluble  salts.  The  freezing-point  of  milk 
is  in  consequence  regular.  There  is  a  constant  relationship 
between  the  specific  gravity  and  the  materials  of  which  the 
milk  is  composed.  This  has  been  brought  out  by  many 
authors  (see  Bibliography),  and  may  be  very  simply  ex- 
pressed by  the  formula  that  the  non-fatty  solids  =  J  of  the 
gravity  +  i  of  the  fat  -f  0-14,  the  fat  being  represented  as 
percentages,  and  the  gravity  being  the  final  figures  of  the 
specific  gravity,  after  removing  the  i-o  which  is  constant  in 
all  milks.  The  composition  of  the  milk  will  vary  according 
to  many  causes  : — 


200  PLANT  PRODUCTS 

(1)  The  period  of  lactation.     Immediately  after  calving, 
the  milk  is  commonly  called  colostrum,  when  the  composition 
is  very  abnormal.    The  total  amount  of  nitrogenous  material, 
albumen,  and  casein  may  be  as  high  as  23  per  cent.,  most  of 
which  is  albumen,  the  casern  being  comparatively  small  in 
amount.     Even  the  second  milking  on  the  first  day  shows 
a  distinct  drop  in  the  percentage  of  albumen  and  casein, 
and  during  the  first  day  the  majority  of  the  figures  that  have 
been  obtained  by  the  author  show  over  10  per  cent,  of  these 
two  substances.     The  third  day  after  calving  brings  the 
figures  down  to  about  6  per  cent,  of  albumen  and  casein. 
By  about  the  seventh  day  the  percentage  of  albumen  and 
casein  has  fallen  to  4  per  cent,  as  against  3^  per  cent,  in 
ordinary  milk.     During  the  same  period  the  milk  sugar 
undergoes  a  very  marked  increase.     On  the  first  day  the 
amount  is  only  about  i  per  cent.,  steadily  rising  until  about 
the  fifth  day,  when  it  reaches  the  normal  figures  between 
4  and  5  per  cent.    The  ash  is  also  usually  high  after  calving. 
From  the  second  to  the  seventh  week  the  greatest  quantity 
of  milk  is  produced,  the  quantity  decreasing  and  the  quality 
improving  after  that.     During  the  last  two  or  three  weeks 
before  going  dry  the  milk  is   usually  of  very  uncertain 
composition,  but  as  the  amount  is  very  small,  little  trouble 
results. 

(2)  In  the  spring,  milk  is  usually  at  its  poorest,  and  in 
November  at  its  richest.     Owing  to  the  disturbance  in  the 
times  of  milking  which  occurs  on  Sunday,  it  is  not  infrequently 
found  that  the  Monday  morning's  milk  is  rather  poor.    The 
difference  between  the  morning  and  evening  milk  follows  a 
fairly  regular  rule,  depending  upon  times  of  milking.     The 
following  formula  represents  the  change   in  composition, 
which  was  obtained  on  an  average  of  a  very  large  number  of 

experiments,  E  —  M  = 6'2,  where  B  stands  for  the  even- 
ing fat  per  cent,  and  M  for  the  morning  fat  per  cent.,  and 
the  e  stands  for  the  interval  between  the  evening  and  morn- 
ing periods  of  milking,  calculated  in  hours.  The  portions 
of  milk  first  drawn  may  contain  only  i  per  cent,  fat,  whilst 


DAIRY  PRODUCTS  201 

the  last  portions  drawn  may  contain  as  much  as  10  per  cent, 
fat. 

(3)  Some  breeds,  such  as  Jerseys,  Guernseys,  and  Kerries, 
give  richer  milk  than  other  breeds,  such  as  Shorthorns  and 
Ayrshires.     Individual  cows  vary  a  great  deal.     Some  short- 
horn cows,  fed  and  housed  under  the  same  conditions,  will 
give  2j  per  cent,  of  butter  fat  and  8  per  cent,  of  non-fatty 
solids,  whilst  others  of  their  companions  will  give  5  per  cent, 
of  butter  fat  and  10  per  cent,  of  non-fatty  solids. 

(4)  When  cows  have  been  fed  indifferently,  they  cannot 
be  expected  to  give  good  quality  milk,  and  under  these 
circumstances  improvements  in  the  system  of  feeding  will 
result  in  a  great  improvement  in  the  quality  of  the  milk, 
but  there  is  a  limit  which  is  soon  reached  as  regards  feeding. 
Overfeeding  does  as  much  harm    as    underfeeding.     With 
skilful  management  the  maximum  of  quality  and  quantity 
can  be  obtained,  and  beyond  this  no  one  can  go. 

(5)  When  milk  stands,  the  cream  rises  to  the  surface, 
especially  in  hot  weather.     In  some  experiments  by  the 
author,  in  hot  weather  the  butter  fat  in  the  top  portion  of 
a  can  increased  from  3  to  7  per  cent.,  in  a  quarter  of  an  hour, 
whilst  the  bottom  portions  decreased  to  2  per  cent.     In 
cold  weather,  however,  a  variation  of  only  i  per  cent,  was 
observed  in  the  same  interval  of  time. 

For  the  production  of  milk  from  plant  products  in  the 
form  of  cattle  food,  it  is  only  on  the  very  best  pastures 
that  satisfactory  results  can  be  obtained  without  the  use 
of  some  of  the  artificial  foods,  and  during  the  winter-time 
artificial  foods  are  always  essential.  Much  can  certainly 
be  done  to  improve  both  pastures  and  hayfields,  and, 
therefore,  reduce  the  consumption  of  higher-class  foods. 
Swedes,  mangolds,  or  yellow  turnips  are  fed  to  cows  in  large 
amounts.  Grass  and  hay  are,  of  course,  of  no  direct  value 
for  human  feeding,  and  mangolds,  etc.,  are  not  worth  much 
as  human  food.  The  cow  can  be  regarded  as  a  machine  for 
the  conversion  of  low-grade  food  into  high-grade  food,  for 
which  purpose  it  is  more  efficient  than  the  fattening  beast. 
Where  the  situation  of  a  farm  is  unsuitable  for  the  delivery  of 


202  PLANT  PRODUCTS 

milk,  milk  can  be  converted  into  butter  and  cheese.  The 
production  of  cream  or  butter  fits  in  well  with  the  rearing 
of  calves,  which  constitutes  an  essential  part  of  the  milk- 
production  problem.  It  is  distinctly  advantageous  that 
the  calf-producing  districts  should  be  well  away  from  the 
large  towns,  and  that  the  milk-producing  districts  should 
be  within  comparatively  easy  reach  of  the  large  towns. 
The  production  of  butter  in  itself  is  not  a  very  economical 
use  to  put  milk  to,  but,  taken  in  conjunction  with  calf 
rearing,  it  is  useful  enough  as  a  side  issue.  The  production 
of  cheese  stands  on  a  higher  plane  as  regards  human  food 
production,  since,  for  each  pound  of  butter,  at  least  three 
pounds  of  cheese  may  be  obtained,  but  if  the  milk  is  turned 
into  cheese,  there  will  be  less  food  available  for  rearing 
calves. 

REFERENCES   TO   SECTION   IV 

"  Clotted  Cream,"  Journ.  Board  of  Agriculture,  1915-16,  p.  105. 

Pegler,  "  The  Goat  as  a  Source  of  Milk,"  Journ.  Board  of  Agriculture, 
1915-16,  p.  642. 

Mohan,  "  The  Manufacture  of  Condensed  Milk,  Milk  Powders,  Casein, 
etc.,"  Journ.  Soc.  Chem.  Ind.,  1915,  p.  109. 

Aikman,  "  Milk,  its  Nature  and  Composition."     (Black.) 

Richmond,  "  Dairy  Chemistry."     (Griffin.) 

Warington,  "  Chemistry  of  the  Farm,"  p.  223.     (Vinton.) 

Maidment,  "  The  Home  Dairy,"  p.  34.     (Simpkin,  Marshall.) 

Collins,  "  The  Composition  of  Milk  in  the  North  of  England,"  Journ. 
Soc.  Chem.  Ind.,  1904,  p.  3. 

Collins,  "  The  Natural  Occurrence  of  Boric  Acid  in  Milk,"  Univ.  Dur. 
Phil.  Soc. 

Collins,  "  Investigations  on  Milk,"  Supplement  Journ.  Board  of  Agricul- 
ture, Nov.  1911,  p.  48. 

Leather,  Analyst,  1914,  p.  432. 

"Inquiry  into  the  Methods  of  sampling  Milk,"  Journ.  Board  of  Agri- 
culture, 1911-12,  p.  30. 

Collins,  "Difference  in  the  Amount  of  Fat  in  Morning  and  Evening 
Milk  owing  to  Uneven  Intervals  of  Milking,"  Proc.  Univ.  Dur.  Phil.  Soc., 
Vol.  IV.  pt.  i ;  Journ.  Board  of  Agriculture,  1911-12,  p.  334. 

St.  John,  "The  Milking  Machine  in  India,"  Agric.  Journ.  Ind.,  1917, 
p.  291. 

Fleischmann,  "  The  Book  of  the  Dairy."     (Blackie  ) 


SECTION  V.— FUTURE  DEVELOPMENT 

Increase  of  Field  Fertility  by  Good  Management. — 

A  very  important  system  by  which  management  can  increase 
the  amount  of  plant  products  is  by  developing  the  amount 
of  grass  and  hay  upon  the  heavier  type  of  land  with  the  aid 
of  basic  slag.  When  a  field  is  under  grass,  and  is  used  for 
grazing,  the  plant  food  contained  in  the  grass  grown  is 
returned  to  the  soil  by  the  cattle  grazing  upon  it,  with  only 
very  small  losses.  When,  however,  the  grass  is  cut  for  hay, 
and  the  hay  fed  to  beasts,  the  manure  will,  for  the  most  part, 
be  given  to  the  lighter  lands.  Hence,  by  means  of  the 
development  of  the  heavy  lands  on  a  farm  by  basic  slag, 
the  lighter  lands  are  indirect^  benefited.  On  the  very  poor, 
heavy  boulder  clay  at  Cockle  Park,  in  Northumberland, 
phosphatic  manure  has  produced  not  merely  double  the 
quantity  of  hay,  but  in  quality  the  hay  is  twice  as  good  as  it 
was  before.  In  practice  considerable  losses  occur  in  storing 
manure,  but  there  is  no  reason  why  they  should  be 
proportionately  greater  with  basic  slag  than  without  basic 
slag.  If,  by  these  means,  the  amount  of  plant  food  added 
to  the  lighter  lands  can  be  practically  quadrupled  by  the 
proper  management  of  the  heavier  lands,  then  a  portion  of 
the  medium  lands  can  be  ploughed  up  and  added  to  the 
arable  lands  of  the  farm.  Moreover,  it  has  been  shown 
time  after  time  that  the  replacement  of  grass  by  arable  lands 
does  not  necessitate  the  lessening  of  the  quantity  of  stock, 
but  quite  the  contrary.  Mr.  A.  D.  Hall  reckons  that  one 
acre  of  wheat  will  produce  four  quarters  grain  and  ij-  tons 
straw.  This  food  material,  fed  to  cattle,  will  produce  256 
Ibs.  of  meat,  or  360  gallons  of  milk.  The  same  land,  under 
grass,  will  produce  i|  tons  of  hay,  giving  120  Ibs.  of  meat, 


204  PLANT  PRODUCTS 

or  1 68  gallons  of  milk.  Both  of  these  estimates  are  on  the 
modest  side.  There  is  plenty  of  land  which,  in  the  past, 
has  been  under  bad  management  and  considered  of  very 
indifferent  quality,  which  to-day,  after  several  years  of 
good  management,  has  been  brought  up  to  the  standard  of 
producing  5  quarters  of  grain,  or  2  tons  of  hay.  Mr.  A.  D. 
Hall  also  shows  that,  on  the  average,  the  arable  land  of  the 
ordinary  farm  is  producing  three  times  as  much  cattle  food 
as  the  permanent  grass. 

Mr.  T.  H.  Middleton  considers  that  on  grazing  land 
the  live  weight  increase  per  acre  varies  from  320  Ibs.  on 
exceptional  pasture,  down  to  as  little  as  50  Ibs.  on  very  poor 
grass.  That  is,  good  land  :  bad  land  ::  6  :  i.  At  Cockle 
Park,  the  plot  grazed  by  sheep,  where  no  improvement  of 
any  sort  has  been  carried  out,  produces  only  22  Ibs.  live 
weight  increase  per  acre  per  annum  (1906-15)  in  the  form 
of  mutton,  although  by  stocking  the  land  with  cattle  and 
sheep,  the  general  experience  at  Cockle  Park  has  been  that 
the  mixture  of  stock  produces  almost  double  the  amount 
of  meat  that  stocking  with  sheep  alone  will  do.  By  treat- 
ment with  basic  slag,  this  same  land  has  been  raised  to  the 
production  of  130  Ibs.  of  live  weight  increase  per  acre  per 
annum,  with  sheep  only,  or  194  Ibs.  live- weight  increase 
per  acre  per  annum  (1906-15)  with  mixed  cattle  and  sheep. 
That  is,  good  management :  bad  management ::  9  :  i.  It 
is,  therefore,  often  found  that  the  very  same  land  may 
show  greater  variations  than  those  of  Mr.  Middleton's 
Minimum  and  Maximum,  according  to  management.  There 
is  not  any  reason  whatever  for  supposing  that  the  improve- 
ment obtained  at  Cockle  Park  might  not  have  been  made  both 
quicker  and  larger  if  considerations  of  financial  caution  had 
not  been  necessary.  Nor  is  there  any  reason  for  supposing 
that  Cockle  Park  is  exceptional. 

In  many  districts  the  prevailing  weather  introduces 
many  risks  in  corn-growing,  but  these  districts  will  often 
grow  large  quantities  of  green  food,  which  can  produce 
greater  amounts  of  milk  or  beef.  There  are  very  large 
areas,  in  almost  all  parts  of  the  country,  where  there  is 


FUTURE  DEVELOPMENTS  205 

hardly  any  corn  grown  at  all,  but  where  the  whole  farming 
industry  turns  upon  the  production  of  milk,  butter,  cream, 
and  calves.  One  may  travel  many  miles  in  some  of  the 
fertile  valleys  of  the  Upper  Tyne,  and  hardly  ever  see  any 
arable  land  at  all.  No  doubt  some  of  the  land  is  too  far 
removed  from  the  rail  and  road,  but  there  is  still  a  large 
area  of  land  which  could  be  used  for  the  growth  of,  at  any 
rate,  oats  and  potatoes. 

Greater  care  is  needed  in  the  storage  of  farmyard  manure. 
Much  loss  occurs  by  drainage,  and  it  is  only  by  persistent 
care  that  this  loss  can  be  reduced  (see  p.  52).  A  greater 
amount  of  artificial  manures  could  also  often  be  satisfactorily 
employed.  Even  where  artificial  manures  have  been  em- 
ployed to  a  fairly  large  extent,  it  will  often  be  found  that 
increasing  quantities  will  still  pay.  It  is  very  rare  indeed 
that  the  amounts  of  manuring  in  practice  are  sufficiently 
large  to  reach  the  stage  when  the  "  I,aw  of  Diminishing 
Returns  "  comes  into  force.  There  is  probably  hardly  any 
enterprise  that  has  been  so  little  exploited  in  this  country 
as  the  land,  consequently  it  is  to  be  expected  that  it  will 
yield  the  best  returns  for  labour  and  capital. 

Economic  Production  of  Meat  in  Winter.— 
Medium  cows  and  bullocks  may  be  taken  to  breathe  out 
about  8  cubic  feet  of  carbon  dioxide  in  an  hour,  and  it  is 
usually  considered  a  good  allowance  to  give  600  cubic  feet 
of  air  space  and  30  square  inches  ventilation  to  each  cow. 
Assuming  a  velocity  of  air  current  equal  to  a  wind  of  one 
mile  per  hour  through  the  opening,  then  the  air  in  motion 
at  the  disposal  of  the  cow  during  one  hour  is  about  twice 
the  air  at  rest  in  the  byre.  Probably  rather  less  than  this 
allowance  is  generally  given,  and  we  may  assume  on  a 
general  basis  that  a  cow  has  to  heat  up  and  moisten  noo 
cubic  feet  of  air.  If  there  were  no  loss  of  heat  by  conduction 
through  the  walls  and  roof,  the  noo  cubic  feet  of  air  passing 
per  hour  through  the  ventilators,  rising  in  temperature 
from  50°  F.  (10°  C.)  to  68°  F.  (20°  C.)  and  evaporating  the 
water  necessary  to  saturate  it,  there  would  be  needed 
239  calories  per  hour.  The  actual  heat  produced  by  the 


206  PLANT  PRODUCTS 

cow  is  1460  calories  per  hour.  It  is  clear  therefore  that  a 
very  large  fraction  of  the  heat  produced  by  a  cow  in  a  byre 
is  lost  by  conduction  of  heat  by  the  walls  and  roof  of  the 
byre.  The  byres,  if  better  constructed,  might  keep  the  cows 
warm,  permit  of  greater  ventilation,  and  yet  save  food. 
It  seems  highly  probable  that  the  waste  of  food  alluded  to 
in  Government  pronouncements  is  often  due  to  faulty 
buildings  compelling  the  practical  farmer  to  use  more  food 
than  is  strictly  necessary,  as  judged  by  careful  trials  con- 
ducted in  buildings  which  are  more  suited  to  the  purpose 
than  many  of  those  that  the  farmer  has  to  make  the  best 
he  can  of. 

If  we  compare  the  type  of  buildings  used  by  cattle  in 
Great  Britain  with  those  in  use  in  Norway,  it  is  very  obvious 
that  the  Norwegian  farmer  has  found  out  by  practice  the 
necessity  of  saving  cattle  food  by  using  warm  buildings.  The 
Norwegian  cattle  byre  is  built  of  wood,  with  double  walls 
and  an  interior  lining  of  hay.  Such  a  structure  provides 
better  ventilation  but  less  draughts  and  less  loss  of  heat 
by  conduction  of  heat  through  the  walls,  and  permits  winter 
feeding  of  cattle  in  a  land  where  cattle  food  is  very  scarce. 

It  would  be  quite  impossible  to  alter  the  cattle  sheds 
during  war  time,  but  much  might  be  done  in  small  ways  by 
the  individual  farmer  if  he  could  be  helped  by  the  local 
advisers  in  agricultural  subjects.  With  the  increase  in  the 
production  of  wheat,  barley,  and  oats  there  will  be  an 
increase  in  the  production  of  straw.  A  good  use  might  be 
made  of  straw  mats  placed  over  ventilators,  doors,  roofs,  etc., 
or  any  exposed  parts  of  the  buildings.  Straw  mats  would 
oppose  but  little  hindrance  to  ventilation.  As  shown 
above  a  very  large  fraction,  say  five-sixths,  of  the  heat 
produced  by  the  cow  is  lost  through  the  walls,  etc.,  of  the 
building.  It  would  take  but  little  improvement  to  save 
some  of  this  and  produce  more  meat  and  milk  with  a  saving 
of  food. 

Development  of  Agriculture  at  Home  and  Abroad. 
— Only  one-fifth  part  of  the  quantity  of  wheat  and  wheat 
flour  necessary  for  human  consumption  is  produced  in 


FUTURE  DEVELOPMENT  207 

the  British  Isles.  The  great  problem  that  is  being  dis- 
cussed at  present  is  how  to  increase  the  amount  of  wheat 
without  decreasing  the  supply  of  meat;  but  by  convert- 
ing grass  land  into  arable  land,  the  amount  of  meat 
produced  need  not  be  decreased.  Which  farms  will  pay 
best  to  produce  grain  and  which  to  produce  meat  will 
depend  upon  the  situation,  and  there  is  little  doubt  that 
one  of  the  chief  difficulties  in  inducing  changes  in  the 
general  farming  of  the  country  lies  in  the  fact  that  what 
is  true  for  the  country  as  a  whole  is  not  necessarily  true  for 
the  individual  farmer,  and  that,  whilst  it  could  be  shown 
readily  enough  in  statistics  that  ploughing  up  grass  land  will 
not  decrease  the  meat,  but  will  increase  the  bread,  yet  from 
the  point  of  view  of  the  farmer,  there  will  often  be  a  need  for 
him  to  alter  his  system  on  lines  which  do  not  correspond 
with  those  of  the  average  of  the  country.  If,  however, 
more  wheat  is  grown  in  the  British  Isles,  less  wheat  must 
certainly  be  imported.  No  doubt  there  would  be  a  tendency 
to  restrict  those  imports  from  foreign  countries,  as  far  as 
possible,  but  it  is  difficult  to  see  how  this  decrease  could  be 
prevented  from  affecting  India  and  the  Colonies.  It  is, 
therefore,  essential  that  each  section  of  the  British  Empire 
should  be  made  more  self-contained. 

In  the  statement  that  only  one-fifth  of  the  wheat  and 
wheat  flour  are  produced  at  home,  reference,  of  course,  is 
made  to  pre-war  conditions .  Probably  to  any  such  estimates 
at  least  20  per  cent,  could  be  added  by  milling  the  wheat, 
so  as  to  avoid  losing  the  outer  nutritious  part  of  the  wheat 
grain,  and  another  10  per  cent,  could  be  added  by  the  use 
of  barley,  without  in  any  way  causing  inconvenience,  but, 
on  the  contrary,  producing  a  better  loaf  than  ever.  The 
attempts  to  introduce  other  grains  have,  however,  in  practice 
not  proved  very  successful.  The  chief  part  of  this  difficulty 
lies  in  the  fact  that  the  starch  grains  of  the  different  cereals 
have  different  temperatures  of  gelatinization,  and,  there- 
fore, the  time  needed  for  cooking  also  differs.  This  difficulty 
is  likely  to  be  still  further  increased  if  potato  flour  is  used 
in  addition,  since  the  gelatinizing  temperature  of  potato 


208  PLANT  PRODUCTS 

flour  and  that  of  rice  flour  differ  by  as  much  as  40°  on  the 
Fahrenheit  scale,  and  it  is,  therefore,  a  practical  impossibility 
to  cook  any  mixture  of  potato  flour  and  rice  flour.  Home 
efforts  at  making  bread  by  first  boiling  the  rice,  oats,  etc., 
independently,  and  then  mixing  with  wheat  flour,  are  satis- 
factory enough,  because  in  this  case  each  part  of  the  flour 
can  be  given  its  own  proper  cooking  (see  p.  118).  In  any 
case,  one  may  say  that  the  20  per  cent,  of  home-produced 
wheat  and  wheat  flour  can  be  made  up  to  25  per  cent, 
without  any  inconvenience  or  any  inj  ury .  Roughly  speaking, 
the  wheat  crops  in  1872  were  about  double  what  they  are  at 
present.  If,  therefore,  we  could  go  back  to  that  condition 
of  affairs,  the  25  per  cent,  could  be  turned  into  50  per  cent., 
that  is,  the  British  Isles  could  be  half  self-supporting  in 
the  matter  of  wheat.  We  are  already  more  than  half  self- 
supporting  in  the  matter  of  meat,  and  the  proposed  changes 
in  the  system  of  agriculture  should  not  affect  these  figures. 

In  addition  to  these  considerations,  one  must  remember 
that  there  are  other  cereals  besides  wheat  which  can  be 
consumed.  The  amount  of  barley  produced  in  the  British 
Isles  is  not  much  behind  the  amount  of  wheat,  and  the 
amount  of  oats  is  very  much  larger.  If  more  motor  ploughing 
comes  into  force,  the  amount  of  oats  necessary  to  maintain 
the  plough  horses  on  the  farm  would  be  reduced,  and  a 
larger  quantity  of  oats  rendered  available  for  human  con- 
sumption, but  unless  motor  ploughing  comes  into  general 
use  the  increase  of  horses  for  ploughing  will  result  in  the 
increase  of  oats  consumed  by  plough  horses.  Potatoes 
are  particularly  suited  for  small  systems  of  cultivation,  and 
much  help  could  be  given  by  town  allotments,  thus  relieving 
the  farmer  of  a  portion  of  his  work,  in  growing  potatoes. 

Experiment  has  shown  that,  with  the  use  of  more  liberal 
dressings  of  artificial  manures,  the  fertility  of  the  land  can 
be  well  maintained,  even  though  white  crops  are  grown 
far  more  frequently. 

Under  the  present  condition  of  high  prices  and  urgency, 
it  would  certainly  be  wise  to  employ  safe  manures,  like 
basic  slag,  with  a  more  lavish  hand,  since  the  conditions 


FUTURE  DEVELOPMENTS  209 

to-day  are  totally  dissimilar  to  those  prevailing  when  any 
agricultural  experiment  was  instituted.  In  Great  Britain 
the  land  has  been  limited  in  amount,  and  there  have  been 
very  good  markets,  but  for  many  years  past  agriculture  has 
been  severely  handicapped  by  lack  of  capital  and  lack 
of  labour  (see  p.  215) . 

The  industrial  farm  is  a  subject  of  much  discussion  to-day. 
By  having  very  large  farms  on  the  industrialized   scheme 
the  number  of  skilled  managers  would  be  reduced,  and  since 
highly  skilled  men  are  scarce,  there  would  be  more  avail- 
able.    In  addition,  such  farms  would  be   able  to  attract 
capital  and  labour  better  than  a  small  farm.     labour  of 
all  kinds,  whether  of  the  highest  or  the  lowest,  is  always 
attracted  to  a  big  concern.     There  is  a  better  security, 
and  there  is  less  interference  with  liberty.  Abroad,  this  work 
has  been  carried  out  for  a  long  time  on  quite  a  large  scale. 
There  are  many  very  large  estates  in  India  and  the  Colonies 
which  have  been  managed  as  industrial  concerns,  and  of 
recent  years  special  industries,  like  rubber,  etc.,  have  been 
added  to  the  list.     Many  of  these  concerns  are  so  highly 
industrialized  that  a  portion  of  their  capital  is  dealt  in  on 
the  stock  exchanges,  but  for  the  most  part  such  concerns 
have  been  in  situations  where  labour  was  plentiful,  a  state 
of  affairs  entirely  distinct  from  that  prevailing  in  the  British 
Isles.     Nevertheless,  even  in  Great  Britain,  one  may  find 
many  instances  of  highly  industrialized  farms.     For  example, 
some   colliery  companies  in  the  northern  counties  manage 
their  agricultural  affairs  like  the  rest  of    their  business. 
Managers,  with  a  scientific  training,  are  appointed,  with 
several  assistant  managers  placed  under  them,  and  the  men 
selected  have,  in  most  cases,  been  given  an  agricultural 
education.    Unfortunately,  as  is  inevitable,  the  industrialized 
farm  does  not  advertise  itself,  and  does  not  tell  the  public 
all  about  how  it  manages  its  own  affairs,  and  it  would  be 
necessary  to  obtain  information  from  the  companies  before 
any  other  industrialized  farm  could  copy  the  methods  of 
those  farms  which  have  been  working  on  this  scale  for 
many  years  past.      In  a  few  cases,  the  managers  of  these 

D.  14 


210  PLANT  PRODUCTS 

industrialized  farms  are  permitted  to  take  one  or  two  pupils. 
Common  sense  would  suggest  that  other  industrialized  farms 
should  secure  the  services  of  such  men.  Nevertheless,  if 
industrialized  farms  are  to  be  pushed  at  a  great  pace,  the 
number  of  men  who  are  qualified  to  take  a  managership 
will  hardly  be  sufficient  to  go  round.  Fortunately,  however, 
we  are  in  a  much  better  position  to-day  to  develop  this  farm 
than  we  were  twenty  years  ago. 

There  is  a  great  contrast  between  the  state  of  affairs  of 
agriculture  in  the  British  Isles  and  in  Germany,  Holland,  and 
Belgium  during  the  last  twenty  or  thirty  years.  It  is  only 
in  Great  Britain  that  land  has  been  going  out  of  cultiva- 
tion. On  the  other  hand,  one  may  find  even  in  Great 
Britain,  that  some  farmers  have  put  small  amounts  of  land 
into  cultivation.  There  are  to  be  found,  all  over  the  country, 
what  Mr.  A.  D.  Hall  very  aptly  calls* the  "  little  farms  bitten 
out  of  the  waste, "'for  one  finds  them  in  Northumberland 
quite  as  frequently  as  in  the  south  country  places  he  mentions, 
and  precisely  as  he  describes  it  for  the  south,  so  it  is  true 
for  the  north,  that  this  work  has  been  carried  out  in  a  slow 
and  unscientific  manner.  Very  little  attempt  has  been  made 
to  find  out  what  the  moors  require.  For  the  most  part, 
they  have  been  surrounded  b}^  walls,  and  stocked  with  cattle. 
Sometimes  the  scheme  happened  to  succeed,  and  sometimes 
success  was  very  small  indeed.  No  serious  attempt  appears 
to  have  been  made  to  discover  whether  the  infertility  was 
due  to  the  absence  of  lime,  or  phosphoric  acid,  or  potash,  or 
whether  it  was  due  to  bad  drainage.  Of  recent  years  a 
few  farmers  have  used  basic  slag  on  such  moor  enclosures, 
but  their  experience  has  been  little  copied  by  their  neighbours, 
and  the  process  of  bringing  in  new  land  has  been  carried  out 
in  a  very  haphazard  manner.  In  considering  the  question 
of  taking  up  new  land  to-day,  the  high  prices  of  labour 
undoubtedly  is  a  serious  difficulty.  Not  merely  is  the  labour 
expensive,  but  the  provision  of  new  buildings  seems  almost 
prohibitive.  On  the  other  hand,  the  increase  in  agricultural 
machinery  offers  some  compensation.  Not  merely  does  it 
reduce  the  actual  cost,  but  it  speeds  up  the  work,  and 


FINANCIAL   ASPECTS  211 

places  the  farmer  in  a  position  of  less  dependence  upon  the 
weather. 

For  an  emergency,  a  country  with  a  considerable  quantity 
of  arable  land  is  much  safer  than  a  country  containing  much 
grass  land.  It  takes,  roughly,  from  8  to  10  Ibs.  of  absolute 
food  of  vegetable  origin  to  produce  i  Ib.  of  absolute  food  in 
the  form  of  meat,  though  some  part  of  that  vegetable  food, 
such  as  grass,  is  of  no  value  for  human  consumption.  The 
advantage  in  an  emergency  of  having  plenty  of  tillage  is  very 
marked,  and  if  it  had  to  be  paid  for  in  normal  times  the 
expense  must  be  looked  upon  as  an  insurance  against  mis- 
fortune. To  develop  agriculture  at  home  it  is  necessary  to 
have  more  capital,  labour,  and  machines.  Farmyard  manure 
must  be  better  stored,  more  land  should  be  cultivated, 
market  gardens  and  allotments  in  the  vicinity  of  towns  must 
be  increased.  As  far  as  possible,  milk  should  be  consumed 
in  preference  to  butter,  but  where  milk  cannot  be  transported, 
owing  to  carriage  difficulties,  more  attention  should  be  paid 
to  the  production  of  cheese. 

Increased  facilities  for  cold  storage  of  summer  milk, 
summer  beef,  and  summer  mutton  would  enable  a  larger 
fraction  of  cattle  food  to  be  derived  from  grass. 

The  Financial  Aspects  of  Agriculture. —The  supply 
of  better  credit  and  capital  to  agriculture  needs  the  earnest 
attention  of  the  Government.  If  the  Government  supply 
a  better  security  as  regards  prices,  an  improvement  in  credit 
will  follow  automatically.  The  mere  fixing  of  a  price  here 
and  there  is  no  solution  of  the  difficulty.  Directly  one 
attempts  to  regulate  prices,  one  must  be  prepared  to  go  in 
for  the  whole  business  thoroughly  and  systematically.  The 
attempt  to  fix  a  maximum  price  for  wheat,  and  no  maximum 
price  for  meat,  has  the  inevitable  result  that  the  farmer 
directs  his  attention  more  to  meat  than  to  wheat,  which  is 
directly  opposite  to  what  is  wanted.  A  complete  scheme 
is  required  before  action  is  taken.  Of  course,  mistakes  are 
bound  to  be  made  at  the  beginning,  but  unnecessary  changes 
should  be  avoided.  It  is  a  rather  striking  fact  that,  in  spite 
of  the  great  rise  in  the  price  of  wheat,  so  little  increase  of 


212  PLANT  PRODUCTS 

cultivation  should,  as  yet,  have  happened,  but  it  must  not 
be  forgotten  that  the  conduct  of  the  business  of  agriculture 
is  essentially  different  from  the  conduct  of  a  retail  shop. 
The  shopkeeper  may  buy  in  a  stock  of  goods  one  day,  and 
sell  most  of  them  within  a  few  days'  time,  and  he  can 
practically  close  his  books  as  far  as  that  transaction  is 
concerned  in  a  very  short  space  of  time.  In  agriculture, 
however,  no  business  affair  of  any  particular  importance 
will  happen  in  less  than  twelve  months,  and  a  farmer  is 
compelled  to  think  more  in  terms  of  four  yearly  rotations 
than  in  shorter  periods  of  time.  As  is  known,  there  is  far 
too  little  capital,  and  far  too  little  labour  for  the  land. 
In  1872,  when  the  amount  of  land  under  cultivation  was 
roughly  double  what  it  is  to-day,  the  average  price  of  cereals 
was  about  405.  a  bushel.  In  1916  it  was  just  under  505.  a 
bushel,  and  in  the  first  half  of  1917  it  was  about  655.  a  bushel, 
yet  it  is  taking  a  large  expenditure  of  energy  to  induce  the 
farmer  to  increase  his  arable  land.  It  is,  therefore,  certain 
that  price  alone  has  very  small  power  indeed  in  causing  a 
change.  Whether  time  and  price  together  might  not  have 
effected  a  change  has  not  yet  been  proved,  but,  considering 
that  prices  have  risen  steadily  for  many  years  before  the 
war,  it  looks  as  though  price  and  time  together  were  not 
sufficiently  powerful  to  make  a  change  in  the  condition  of 
agriculture,  and  that  some  other  considerations  will  have 
to  be  taken  into  account.  Nevertheless,  the  money  side 
of  the  question  is  very  important,  and  must  be  considered. 
There  is  the  position  of  the  landlord  to  consider.  What  money 
he  has  made  out  of  the  land  has  chiefly  been  by  sales,  and 
not  by  cultivation,  and  he  has  found  all  his  amusement  out 
of  sport,  and  very  little  out  of  the  cultivating  side  of  country 
life.  From  his  point  of  view,  therefore,  crop  production 
does  not  appear  very  important,  and  has  been  neglected. 
The  farmer  has  to  make  a  living  out  of  farming ;  he  will 
not  change  from  grass  to  tillage  unless  he  sees  his  way  to 
make  more  money  out  of  it.  Mr.  A.  D.  Hall  gives  figures 
which  suggest  that  grazing  can  produce  returns  to  cover 
interest,  sinking  fund,  profit,  management,  etc.,  of  about  27 


FINANCIAL  ASPECTS  213 

per  cent,  on  the  capital  sunk,  as  against  17  per  cent,  for 
arable  land.  That  is,  of  course,  under  past  prices,  but 
obviously  if  prices  for  meat,  milk,  corn,  and  labour  all  go 
up  proportionately,  it  does  not  alter  the  relative  position 
of  the  two  systems  of  farming.  It  is  not  so  much  the  absolute 
price  of  wheat  that  is  so  important,  as  the  ratio  of  the  price 
of  wheat  to  the  price  of  meat  that  will  determine  the  relative 
proportions  of  arable  to  grass  land,  and  that  is  why  the  rise 
in  price  has  produced  so  little  effect.  Once  the  State  begins 
to  interfere  in  the  question  of  prices,  it  is  almost  driven  into 
considering  what  kind  of  partial  ownership  of  the  land  will 
have  to  be  adopted  by  the  State.  By  means  of  the  Excess 
Profits  Tax  it  is  obvious  that  the  State  can  assume  a  large 
share  in  any  industry.  At  present  the  State  is  taxing  excess 
profits  at  the  rate  of  80  per  cent.,  that  is  to  say,  the  State 
occupies  the  same  position  towards  the  industries  of  the 
country  as  the  holders  of  founders'  shares  in  an  ordinary 
industrial  concern  do.  There  are  many  concerns  where  there 
are  a  small  number  of  such  founders,  who  in  bad  times 
receive  no  dividends  but  in  good  times  obtain  a  quite 
disproportionate  share  of  the  profits.  Under  a  type  of 
taxation  such  as  we  have  at  present,  the  State  is  undoubtedly 
part  owner  of  all  the  industries  that  are  under  excess  profits 
taxation.  If  the  Government  were  to  put  all  concerns  which 
deal  in  human  food  on  the  same  basis,  the  State  would 
become  a  partner  in  the  whole  of  these  businesses,  including 
land,  and  this  is  a  point  which  has  to  be  carefully  considered. 
The  present  position  of  affairs  in  the  British  Isles  is  not 
altogether  dissimilar  to  the  state  of  affairs  in  India,  when  the 
chaos  and  disorganization,  resulting  from  the  complete  break- 
up of  central  authority,  induced  the  British  East  India 
Company,  and  later  the  Crown,  to  adopt  the  attitude  that 
the  land  belonged  to  the  State,  and  that  the  State  must 
assess  what  rent  should  be  paid.  When  prices  rise,  and  the 
supply  of  labour  fails,  and  both  are  partly  controlled  by 
the  State,  then  the  difference  between  State  ownership  and 
such  a  condition  of  affairs  is  not,  after  all,  a  big  one, 
and  it  would  be  wise  to  consider  the  attitude  of  the  State 


214  PLANT  PRODUCTS 

towards  a  part  ownership,  which  is  already  effective  if 
unacknowledged; 

The  relationship  between  the  price  of  grain  and  the  wages 
of  labour  must  always  determine  the  amount  of  labour 
available  upon  the  farm.  The  discussion  of  a  possible 
sliding  scale  between  prices  and  wages  presents  many 
difficulties,  but  sliding  scales  have  been  adopted  in  other 
industries  which,  in  spite  of  their  crudity,  have  been  success- 
ful. The  sliding  scale  which  affects  the  price  of  gas  and  the 
dividends  of  shareholders  has  played  a  very  useful  part, 
though  it  would  be  difficult  to  conceive  a  more  hopelessly 
crude  basis  than  that  on  which  it  was  founded. 

The  amount  of  capital  per  acre  in  England  is  about  £7, 
whereas  in  former  days  it  was  much  higher,  £10  per  acre 
being  regarded  as  a  kind  of  minimum.  Other  parts  of 
Western  Europe  have  needed  capital  of  £20  per  acre.  Capital, 
in  agriculture,  stands  in  a  rather  different  position  to  what  it 
does  in  many  other  industries,  because  in  agriculture  currency 
also  occupies  a  different  position.  In  primitive  farming, 
currency  is  practically  negligible.  Currency  to-day  stands 
also  in  a  peculiar  position,  but  Great  Britain  has  been  far  less 
affected  than  other  countries  in  this  respect.  The  currency  of 
this  country  is  supposed  to  rest  on  a  gold  basis,  and  nominally 
the  treasury  note  is  payable  in  gold  at  the  Bank  of  England. 
In  Germany,  the  gold  currency  is  practically  suspended. 
The  German  Government  paper  bond  for  ten  kilogrammes 
of  potatoes  is  honoured  at  the  proper  place  for  dealing 
with  those  articles,  but  the  German  Government  paper 
bond  for  a  weight  of  gold  corresponding  to  twenty  marks  is 
not  honoured  at  the  place  commonly  dealing  in  gold.  It 
would  be,  therefore,  more  correct  to  say  that  Germany  has  a 
potato  currency  than  that  she  has  a  gold  currency. 

Money  plays  no  practical  part  in  the  business  of  Indian 
agriculture.  It  is,  therefore,  perfectly  possible  to  conduct 
agriculture  without  currency,  but  it  would  be  incorrect 
to  say  that  an  Indian  village  had  no  capital,  because  it  has 
houses,  implements,  etc.,  but  such  capital  is  very  immobile. 
Not  very  many  years  ago  the  farmer  in  Great  Britain  had 


THE  LABOUR   QUESTION  215 

large  stocks  of  bacon  and  other  commodities ;  to-day  he 
depends  much  more  upon  the  local  shops.  The  capital  in 
commodities  has  decreased  quite  as  strikingly  as  the  capital 
acknowledged  by  the  bank. 

It  is  always  well  to  look  to  the  future,  and  we  ourselves 
may  be  placed  in  straits  like  Germany.  Should  that  be  so, 
it  will  be  worth  considering  whether  we  should  not,  as  a 
nation,  adopt  a  logical  position  and  start  an  institution 
which  would  amount  to  a  wheat  bank,  with  wheat  bonds 
and  wheat  deposits,  paid  for  both  in  regard  to  capital  and 
interest  in  terms  of  wheat.  Perhaps  some  of  the  difficulties  of 
supplying  agriculture  with  the  necessary  capital  could  be 
overcome  if  we  more  frankly  recognized  that  in  the  past 
agricultural  capital  has  not  altogether  depended  upon  the 
acknowledged  currency,  but  has  depended  very  largely  upon 
the  currency  of  commodities  and  custom.  To  the  old- 
fashioned  British  farmer  capital  means  fat  stock  and  a  full 
stackyard,  whilst  currency  means  bacon  and  potatoes; 
and  to  the  Indian  villager  currency  is  dastoor  and  capital 
a  bullock.  By  returning  to  some  of  our  old  ideas  we  might 
reduce  the  strain  resulting  from  the  •  lack  of  that  capital 
which  has  come  to  be  denned  in  terms  suited  only  to  the 
city  bank. 

The  Labour  Question. — Many  of  the  difficulties  of  agri- 
culture during  the  last  fifty  years  have  arisen  from  the  fact 
that  the  old  industries  which  used  to  exist  in  the  country 
have  migrated  to  the  towns.  The  agricultural  population  of  a 
hundred  years  ago  was  not  purely  dependent  upon  agriculture, 
but  was  partly  dependent  upon  rural  industries,  and  it  is 
not  quite  correct  to  say  that  when  the  rural  population 
removed  to  the  towns  they  were  leaving  their  old  employ- 
ments. In  part,  they  merely  followed  their  old  employments. 
To  foster  rural  industries  is  part  of  the  business  of  agricultural 
development,  and  the  full  utilization  of  all  woods  and  forests 
is  a  natural  part  of  rural  economy.  Whilst  it  is  true  that 
arable  land  may  produce  twice  as  much  food  as  grass  land, 
it  would  take  nearly  ten  times  as  much  labour  to  obtain 
such  a  result.  And  where  is  this  labour  to  come  from  ?  The 


2i6  PLANT  PRODUCTS 

effective  labour  of  one  man,  however,  shows  the  greatest 
conceivable  variations.  It  is  very  difficult  to  represent  this 
in  any  very  definite  terms,  but  Government  statistics  enable 
us  to  make  some  rough  calculations,  from  which  I  should 
conclude  that  one  British  agricultural  worker  by  his  labours 
feeds  about  eight  persons,  one  German  agricultural  worker 
feeds  about  four  persons,  and  one  Indian  agricultural  worker 
can  feed  no  more  than  two,  on  the  same  scale  of  diet.  How- 
ever much  doubt  may  be  thrown  upon  the  validity  of  any 
such  crude  calculations,  the  order  of  merit  in  the  three 
cases  is  not  likely  to  be  seriously  affected.  The  British 
agricultural  worker  has  been  far  the  most  efficient.  There 
are  several  reasons  why  such  great  differences  are  easily 
explainable.  The  "  lyaw  of  Diminishing  Returns  "  applies 
with  quite  as  much  force  to  labour  as  it  does  to  fertilizers. 
Indeed,  this  is  almost  a  self-evident  proposition.  A  piece  of 
land  growing  nothing  but  weeds,  with  its  first  increment  of 
labour,  will  add  hardly  anything  for  human  consumption, 
but,  as  more  and  more  labour  is  expended  upon  it,  its 
fertility  rises,  till,  after  a  certain  point,  its  limit  is  reached, 
and  further  labour  does  no  good.  It,  therefore,  is  inevitable 
that  there  must  be  some  point,  in  the  application  of  labour 
to  the  soil,  when  a  maximum  of  efficiency  of  labour  is 
reached,  after  which  the  more  work  put  upon  the  land  the 
less  is  the  return  per  unit  of  labour. 

Further  increase  of  arable  land  means  taking  up  land 
which  is  less  suited  for  the  purpose  and  putting  upon  the 
land  labour  which  is  also,  on  the  average,  less  suitable. 
It  is,  therefore,  urgently  necessary  to  consider  how  the 
efficiency  of  labour  is  to  be  increased,  in  order  that  we  may 
counteract  the  inevitable  tendency  to  produce  less  per  head 
of  labour  employed. 

As  regards  the  quantity  of  labour,  there  is  a  considerable 
risk  that  England  may  lose  her  open-air  population  after 
the  war,  just  exactly  when  she  wants  it  most.  The  future 
may  show  that  we  are  less  prepared  for  peace  than  we  were 
for  war.  Both  old  and  new  sources  of  labour  must  be  directed 
to  the  land.  There  are  a  large  number  of  men  who  were 


THE  LABOUR   QUESTION  217 

previously  employed  merely  as  routine  clerks  and  shop 
assistants,  who  have  now  become  accustomed  to  an  outdoor 
life.  They  will  be  very  unwilling  to  go  back  to  indoor  life, 
and  it  is  now  the  time  to  consider  whether  their  wishes 
and  the  country's  needs  might  not  be  united.  Much  of  this 
routine  work  is  now  being  done  by  women  who  will  at  the 
end  of  the  war  be  more  efficient  than  the  returned  soldiers. 
The  returned  soldier  will  have  learnt  the  use  of  spade  and 
pick  and  be  more  suited  to  agriculture  or  forestry.  Those 
men  who  are  of  exceptionally  high  mental  ability,  but  belong 
to  a  somewhat  low  physical  category,  will  all  be  needed 
for  the  professions,  skilled  trades,  and  directorships.  In 
agriculture  there  is  room  for  both  those  who  have  a  higher 
degree  of  mental  ability,  and  those  who  are  chiefly  physically 
strong.  One  thing  is  clear,  we  shall  not  need  any  compulsion  ; 
we  shall  only  need  encouragement  and  proper  facilities. 
Among  the  sources  under  Government  control  there  are 
nearly  a  quarter  of  a  million  of  Poor  Law  children,  many  of 
whom  might  be  trained  specially  for  the  land. 

As  regards  the  efficiency  of  labour  it  should  be  noted 
that  no  little  part  of  farm  labour  has  been  carried  out  by 
the  "  sweated  labour  "  of  the  family  of  the  small  or  medium- 
sized  farmer.  There  are  many  farmers,  especially  at  the 
present  time,  every  member  of  whose  family  is  working 
sixteen  hours  a  day.  Such  a  state  of  affairs  is  not  in  the 
interests  of  the  nation.  At  least  one  of  the  causes  which 
have  driven  men  from  the  land  has  been  the  excessive  hours 
of  labour.  Of  course,  one  hour  of  labour  in  the  factory  is 
not  the  same  as  one  hour  of  labour  on  the  field.  The  factory 
is  more  unhealthy,  and,  therefore,  more  exhausting.  Never- 
theless, however  great  the  amelioration  may  be,  the  hours 
of  labour  on  the  land  are  not  infrequently  excessive,  and 
probably  do  not  conduce  to  efficiency. 

As  regards  the  economy  of  labour  one  of  the  great 
difficulties  on  a  farm  is  the  heavy  work,  due  to  bad  roads, 
not  merely  on  the  horses  but  also  on  the  men.  These 
difficulties,  however,  are  most  strongly  marked  on  farms 
which  are  largely  under  grass,  and  if  the  grassland  is  ploughed, 


2i8  PLANT  PRODUCTS 

the  construction  of  roads  must  also  be  undertaken.  Both 
the  quantity  and  quality  of  labour  are  intimately  concerned 
with  the  supply  of  proper  accommodation.  The  lack  of 
cottages  is  undoubtedly  very  serious  in  England,  but  it  is 
not  so  serious  in  Ireland,  where  there  are  very  large  numbers 
of  cottages,  uninhabitable  at  present  but  possible  to  repair. 

Undoubtedly  the  climate  of  Ireland  is  not  that  of  a  corn- 
growing  country,  but  the  use  of  basic  slag  and  lime  would 
produce  more  milk,  butter,  cheese,  and  calves,  and  thus 
relieve  the  English  farmer  of  part  of  this  work.  As  regards 
machinery,  very  great  progress  has  already  taken  place 
in  machines  for  reaping  grain  and  mowing  hay,  and  it  does 
not  seem  likely  that  further  progress  can  be  of  a  very  striking 
character.  Milking  machines  have  now  reached  a  thoroughly 
practical  condition,  and  economize  labour  in  a  very  striking 
manner.  They  are  not  suitable  for  very  small  holders, 
although  satisfactorily  used  on  farms  which  have  only 
twenty  cows.  The  motor  tractor  and  plough  are  not  so 
advanced,  but  if  men  could  be  trained  to  understand  both 
the  machinery  and  the  land,  the  efficiency  of  these  machines 
could  be  enormously  improved.  These  machines  have, 
however,  undoubtedly  come  to  stay,  and  every  effort  should 
be  made  to  overcome  the  difficulties  in  connection  with 
them. 

If  we  have  to  increase  both  quantity  and  quality  of 
labour,  we  must  provide  a  proper  step  to  enable  the  labourer 
to  rise  in  the  world.  Undoubtedly  one  of  the  great  attractions 
of  town  life  lies  in  the  fact  that  a  man  has  a  much  better 
chance  of  advancement.  Whatever  the  merits  or  demerits 
of  smallholdings  may  be,  they  provide  a  very  valuable  step 
between  farm  labourers  and  farmers,  and  even  if  small- 
holdings were  not  in  themselves  very  efficient  food  producers, 
it  would  still  be  worth  while  pushing  them,  to  encourage 
labour. 

The  only  cure  for  the  unsatisfactory  conditions  of  buying 
and  selling  among  smallholders  seems  to  be  some  system 
of  co-operation.  It  is  difficult  to  see  how  any  system  of  co- 
operation among  smallholders  can  be  superior  to  that  which 


EDUCATION  219 

still  exists  in  an  Indian  village,  the  inhabitants  of  which 
are  more  at  the  mercy  of  the  money-lender  and  grain  dealer 
than  we  would  wish  our  smallholders  to  be.  Nevertheless, 
the  enormous  strides  which  have  been  made  in  modern 
co-operation  in  India,  and  elsewhere,  lead  one  to  hope  that 
much  may  be  achieved  in  this  direction.  In  considering 
the  labour  of  the  country,  we  must  also  consider  the  town 
labourer.  At  present,  of  our  total  consumption  of  wheat, 
only  19  per  cent,  is  home  grown,  as  against  75  per  cent,  of 
oats.  Yet  we  each  eat  twice  as  much  wheat  as  oats.  In  a 
similar  way,  we  produce  practically  all  the  potatoes  we  eat, 
as  against  only  19  per  cent,  of  the  wheat  we  eat,  yet  our 
consumption  per  head  of  wheat  is  greater  than  that  of 
potatoes.  Are  the  town  workers  willing  to  change  their 
diet  so  as  to  make  the  consumption  more  nearly  fit  the 
production  ?  We  ought  to  consume  more  home-grown 
food  and  less  foreign-grown  food.  The  town  workers  may 
have  to  learn  to  eat  less  wheat  but  more  barley,  oats,  and 
potatoes.  -Undoubtedly  the  chief  reason  why  our  consump- 
tion of  wheat  is  so  high  is  because  wheat  lends  itself  to  the 
production  of  bread,  which  can  be  purchased  ready  cooked, 
whilst  barley,  oats,  and  potatoes  all  need  some  treatment  at 
home  before  they  can  be  rendered  fit  for  consumption. 
Germany  has,  to  some  extent,  solved  the  problem,  by 
producing  large  quantities  of  dried  potato  flour.  As  it 
happens,  dried  potato  flour  is  more  suited  for  mixing  with 
wheat  than  either  barley  or  oats  for  the  production  of  bread, 
because  potato  starch  gelatinizes  at  a  temperature  below 
that  of  wheat  starch,  whilst  barley  and  oats  require  higher 
temperatures  for  cooking. 

I/abour  must,  however,  be  considered  in  relationship  to 
other  factors  determining  plant  production.  The  trouble  in 
Great  Britain  is  that  the  supply  of  land  has  been  in  excess 
of  the  land  we  were  willing  to  cultivate,  and  that  the  labour 
that  the  farmer  could  afford  to  pay  for  has  been  insufficient 
for  that  cultivation.  The  ratio  of  labour  to  land  must  be 
increased  to  obtain  an  increased  plant  production,  and, 
since  the  land  in  the^British  Isles  is  almost  a  fixed  quantity, 


220  PLANT  PRODUCTS 

labour  must  therefore  be  increased,  and  to  increase  the 
efficiency  of  labour  the  ratio  of  machinery  to  men  must  be 
increased,  and  also  the  ratio  of  manure  to  land  must  be 
increased  in  order  to  economize  labour.  Where  much  hand 
work  can  be  put  into  the  soil,  very  large  crops  can  be  raised, 
without  the  expenditure  of  much  manure.  Extra  labour  will, 
indeed,  cure  many  of  the  troubles  which  the  land  suffers  from, 
although  it  may  sometimes  be  more  economical  to  employ  the 
soil  fertilizers  described  in  the  earlier  parts  of  this  volume. 
To  increase  the  efficiency  of  labour,  one  must  also  consider 
the  question  of  management.  One  of  the  difficulties  in  the 
way  of  industrialized  farms  is  that  the  ratio  of  managers 
to  men  must  decrease,  since  the  employment  of  many 
managers  would  ruin  the  balance  sheet.  It  will  probably 
be  found  that  there  is  a  limit  to  the  industrialization  of 
agriculture,  because,  if  you  decrease  the  ratio  of  management 
to  labour,  the  labour  will  gradually  become  more  and  more 
inefficient.  Moreover,  we  require  to  increase  the  yield  per 
acre  as  much  as  anything  else.  It  is  the  last  quarter  of 
grain  that  takes  the  greatest  amount  of  management,  labour 
and  manure  to  obtain.  High  farming  is  only  possible  with 
high  prices,  and  unless  the  town  labourer  is  prepared  to 
pay  these  high  prices,  and  thus  support  his  companion  on 
the  farm,  increased  plant  production  becomes  impossible. 
If  prices  are  increased,  wages  must  also  be  increased.  If 
the  farmer  pays  out  much  larger  amounts  of  money  for  wages, 
he,  like  any  other  business  man,  must  make  larger  profits  to 
pay  for  the  risks  and  interest  on  the  capital  that  he  handles, 
and,  indeed,  this  is  truer  of  the  farmer  than  it  is  of  many 
other  business  men,  because  the  interval  between  the  time 
when  he  has  to  pay  out  and  the  time  when  he  begins  to 
receive  is,  on  the  average,  not  less  than  six  months. 

Education. — Education  concerns  all  classes  on  the 
land.  The  landowner  himself  must  be  prepared  to  study 
agriculture  seriously,  and  to  send  his  sons  to  receive  an 
agricultural  education.  At  present  the  landowner  is  content 
to  send  his  son  to  the  University  for  a  purely  classical 
style  of  education,  whereas  he  should  prefer  his  son  to 


EDUCATION  221 

be  educated  in  agricultural  technology.  He  is  the  trustee 
on  behalf  of  the  nation  for  the  proper  management  of  the 
land  under  his  control,  and  his  sons  will  have  ultimately 
to  take  his  place,  and,  meanwhile,  must  act  as  his  deputy. 
The  exact  type  of  education  that  is  best  suited  to  the  land- 
owner or  his  son  has  yet  to  be  evolved,  but  it  cannot  possibly 
be  evolved  without  the  landowner's  active  participation. 
If  the  landowner's  sons  came  to  the  University  in  sufficient 
numbers,  the  type  of  education  given  would  adjust  itself 
to  suit  their  needs.  Further,  the  bailiffs  appointed  by  the 
landowners  to  manage  some  part  of  their  estate  should  be 
better  paid  and  better  educated  men,  who  would  be  in  a 
position  to  set  an  example  to  the  tenant  farmers  Agriculture 
possesses  the  great  disadvantage  of  being  situated  away 
from  the  centres  where  much  of  the  education  is  given,  but, 
as  it  is  in  the  interests  of  the  country  that  agriculture  should 
be  advanced,  it  is  necessary  that  money  and  energy  should 
be  expended  upon  rural  schools,  even  if  the  expenditure 
appears  out  of  proportion  to  the  number  of  those  attending. 
It  is  difficult  to  form  any  very  general  opinion  as  to  how 
much  of  the  energy  expended  on  agricultural  education 
has  so  far  produced  direct  results.  L,ike  all  other  teachers, 
those  engaged  in  teaching  agriculture  cannot  possibly  keep 
in  touch  with  the  after-history  of  all  their  pupils.  It  is, 
however,  possible  to  compile  a  list  of  those  that  one  does 
keep  in  contact  with,  and  assume  that  those  one  loses  touch 
with  exhibit  the  same  ratio  as  those  one  knows.  The 
Armstrong  College  Agricultural  Students'  Association  was 
originally  founded  for  the  purpose  of  keeping  in  touch  with 
old  students,  and  the  latest  published  proceedings  of  that 
Association  show  that,  of  the  164  members  who  have  kept 
in  contact  with  the  Association,  there  are  70  known  to  be 
farming,  there  are  9  known  to  have  received  an  agricultural 
education  and  known  not  to  be  farming,  there  are  19  who 
were  not  educated  in  agricultural  subjects,  but  who  are  now 
taking  some  part  in  assisting  agriculture.  The  term  "farm- 
ing "  as  given  in  the  above,  includes  those  who  are  managing 
farms  on  somebody  else's  account  as  well  as  those  who  are 


222  PLANT  PRODUCTS 

actually  farming  with  their  own  capital.  So  far,  therefore, 
as  such  figures  go,  the  energy  of  the  teacher  which  has  been 
lost  is  counterbalanced  by  the  energy  which  goes  into 
agriculture. 

One  Bachelor  of  Science  is  farming  on  his  own  account, 
another  is  managing  on  behalf  of  a  big  company,  and  as  far 
as  one  can  see,  the  education;  even  of  the  most  scientific 
type,  has  produced  most  admirable  practical  results,  whether 
expressed  in  terms  of  so  much  food  material,  or  of  so  much 
cash  profit. 

I  do  not  know  that  there  can  be  any  more  complete  proof 
that  the  labours  of  those  who  are  engaged  in  teaching 
agricultural  subjects  in  Armstrong  College  has  been  fully 
utilized  for  the  cultivation  of  land  and  plant  production. 
Whether  the  agricultural  education  in  any  other  district 
has  been  equally  satisfactory  can  only  be  decided  by  those 
who  are  intimately  connected  with  that  district,  but  Govern- 
ment statistics  show  that  there  is  no  reason  for  supposing 
that  these  results  are  exceptional.  Agriculture  has  certainly 
used  the  advancements  of  science  quite  as  readily  as  any 
other  industry  in  the  country,  which  is  but  faint  praise. 

REFERENCES   TO   SECTION   V 

Middle  ton,  "  The  Farmer  and  Self-Improvement,"  Journ.    Board   of 

Agriculture,  1916-17,  p.  760. 

Hall,  "  Agriculture  after  the  War,"  pp.  31,  32.     (Murray.) 

Middleton,  "  Systems  of  Farming  and  the  Production  of  Food,"  Journ. 

BoarS  of  Agriculture,  1915-16,  p.  520. 

Baden-Powell,  "  Land  Systems  of  British  India,"  p.  282.     (Clarendon 

Press.) 

"  The  Food  Supply  of  the  United  Kingdom,"  Journ.  Soc.  Chem.  Ind., 

1917,  p.  279. 

Drage,  "  The  Imperial  Organization  of  Trade,"  p.  285.     (Smith.) 
Hobson,  "  Gold  Prices  and  Wages,"  p.  129.     (Methuen.) 
Simpson,  "  Co-operative  Credit,"  Agric.  Journ.  India,  1906,  p,  131. 
Gourlay,  "  Co-operative  Credit  in  Bengal,"  Agric.  Journ.  India,  1906, 

p.  217. 

Matthai,  "  Village  Government  in  British  India,"  p.  17.    (Fisher  Unwin.) 
Green,  "  The  Rural  Industries  of  England,"  p.  146.     (Marlborough.) 
Report  of  the  Board  of  Agriculture,  Cd.  6151,  1912,  p.  31. 
Smetham,    "Present    Conditions    in    Relation    to    Food    Supplies." 

(Toulmin,  Fishergate,  Preston.) 

Wood,  "  The  National  Food  Supply  in  Peace  and  War."     (Cambridge 

University  Press.) 

Noyes,  "  Financial  Chapters  of  the  War,"  pp.  34,  44.     (Macmillan.) 
Cunningham,  "The  Progress  of  Capitalism  in  England,"  p.  40.     (Cam- 
bridge University  Press.) 


GENERAL   BIBLIOGRAPHY  223 

Turner,  "  The  Land  and  the  Empire."     (Murray.) 

"Occupations  of  Agricultural  Students  after  leaving  College,"  Journ. 
Board  of  Agriculture,  1911-12,  p.  848. 

"  Agricultural  Credit  and  Co-operation,"  Journ.  Board  of  Agriculture, 
1912-1913,  p.  43. 

"  Improvement  of  Poor  Hill  Pasture,"  Journ.  Board  of  Agriculture, 
912-13,  p.  352. 

Wibberley,  "Continuous  Cropping,"  Journ.  Board  of  Agriculture, 
1914-1915,  p.  817. 

Clouston,  "  Rural  Education  in  its  Relation  to  Agricultural  Develop- 
ment," Agric.  Journ.  India,  1917,  P-  216. 

Allen,  "The  Housing  of  the  Agricultural  Labourer, "  Journ.  Roy.  A  gric. 
Soc.  Eng.,  1914,  p.  20. 


GENERAL  BIBLIOGRAPHY 

[The  sectional  references,  which  foim  part  of  the  Bibliography,  are 
given  at  the  end  of  each  section,  and  maybe  readily  traced  by  consulting 
the  Contents  Table,  pp.  xi.-xvi.] 

(i)  ENCYCLOPEDIA  AND  JOURNALS 

Encyclopaedia  Britannica. 

Wiley,  "  The  Principles  of  Agricultural  Analysis."  (Chemical  Publish- 
ing Co.) 

Thorpe,  "  Dictionary  of  Applied  Chemistry."     (Longmans.) 

Newsham,  "  The  Horticultural  Note-Book."     (Crosby  Lockwood.) 

Primrose  McConnell,  "  The  Agricultural  Note-Book.  (Crosby  Lock- 
wood.) 

Wright,  "  A  Modern  Encyclopaedia  of  Agriculture."  (Gresham  Pub- 
lishing Co.) 

The  Journal  of  the  Board  of  Agriculture.  (The  Board  of  Agriculture 
and  Fisheries.) 

The  Agricultural  Journal  of  India.  (Thacker,  London;  Thacker, 
Spink,  Calcutta.) 

The  Journal  of  Agricultural  Science.     (Cambridge  University  Press.) 

The  Journals  of  the  Royal  Agricultural  Society,  the  Chemical  Society, 
and  the  Society  of  Chemical  Industry. 

(2)  AGRICULTURE 

Somerville,  "  Agriculture."     (Williams  &  Norgate.) 
Shaw,  "  Market  and  Kitchen  Gardening."     (Crosby  Lockwood.) 
Hall,  "  An  Account  of  the  Rothamsted  Experiments."     (Murray.) 
Middleton,    "The    Recent    Development    of    German    Agriculture." 

[Cd.  8305.] 

Fream,  "  Elements  of  Agriculture."     (Murray.) 

James  Macdonald,  "  Stephen's  Book  of  the  Farm,"     (William  Bryce.) 

Voelcker,  "  Improvement  of  Indian  Agriculture."     (Eyre  and  Spottis- 

wood.) 

Mukerji,    "Handbook    of    Indian    Agriculture."      (Thacker,    Spink, 

Calcutta.) 

Geerligs,  "  The  World's  Cane  Sugar  Industry."    (Rodger,  Manchester.) 
Vorhees,  "  Fertilizers."     (Macmillan.) 


224  GENERAL  BIBLIOGRAPHY 

(3)  CHEMISTRY 

Addyman,  "  Agricultural  Analysis :  A  Manual  of  Quantitative  Analysis." 

(William  Bryce.) 

Snyder,  "  Chemistry  of  Plant  and  Animal  Life."     (Macmillan.) 

Fritsch,  "  The  Manufacture  of  Chemical  Manures."     (Scott  Greenwood. ) 

Cousins,  "  The  Chemistry  of  the  Garden."     (Macmillan.) 

Warington,  "  Chemistry  of  the  Farm."     (Vinton.) 

Hopkins,  "  Soil  Fertility  and  Permanent  Agriculture."     (Ginn.) 

Hilgard,  "  Soils."     (Macmillan.) 

Collins,  "  Agricultural  Chemistry  for  Indian  Students."      (Government 

of  India  Central  Printing  Office,  Calcutta.) 

Hall,  "  The  Feeding  of  Crops  and  Stock."     (Murray.) 

Hall,  "  The  Soil."     (Murray.) 

Johnson,  "  How  Crops  Grow."     (Orange  Judd  Company.) 

Russell,  "  Soil  Conditions  and  Growth."     (Longmans.) 

Hall,  "  Fertilizers  and  Manures."     (Murray.) 

Cameron  and  Aikman, "  Johnston's  Elements  of  Agricultural  Chemistry." 

(Blackwood.) 

Johnson,  "How  Crops  Feed."     (Orange  Judd  Company.) 

Bernard  Dyer,  "  Fertilizers  and  Feeding  Stuffs."     (Crosby  Lockwood.) 

Chamberlain,  "Organic  Agricultural  Chemistry."     (Macmillan.) 

Tibbies,  "Foods."     (Bailliere,  Tindall  &  Cox.) 

Ingle,  "  Manual  of  Agricultural  Chemistry."     (Scott,  Greenwood.) 

Storer,    "  Agriculture    in    Some    of    its    Relations    with    Chemistry." 

(Sampson  Low.) 

Haas  and  Hill,  "  An  Introduction  to  the  Chemistry  of  Plant  Products." 

(Longmans  &  Co.) 

Fowler,  "  Bacteriological  and  Enzyme  Chemistry."     (Arnold.) 
Roscoe  and  Schorlemmer,  "  Treatise  on  Chemistry."     (Macmillan.) 
Bennett,  "  Animal  Proteids."     (Bailliere,  Tindall  &  Cox.) 

(4)  ECONOMICS 

Theodore  Morrison,  "  The  Economic  Transition  in  India."     (Murray.) 

Radhakamal  Mukerjee,  "  The  Foundation  of  Indian  Economics." 
(Longmans  &  Co.) 

Leather,  "  The  Agricultural  Ledger,  1898,"  No.  2.  (Government 
Printing  Office,  Calcutta.) 

Money's  Fiscal  Dictionary.     (Methuen.) 

Fisher,  "  The  Purchasing  Power  of  Money."     (Macmillan.) 

Dunlop,  "  The  Farm  Labourer."     (Unwin.) 


INDEX 


(Chief  References  are^in  heavy  type.) 


ABYSSINIA,  144 

Acacia,  132,  162 

Acetate  of  lime,  125,  130 

Acetates,  152 

Acetic  acid,  103,  125,  129,  164 

Acetone,  103,  130,  136 

Acetylene,  88 

Acid  vapours,  168 

Addyman,  223 

Aeration,  4 

Aerobes,  50 

Africa,  30 

Agar,  7,  132 

Aikman,  202 

Air,  2,  7,  20,  82,  205 

Albumen,  109..  147,  200 

Albuminoids,  109,  174,  181 

Albuminoid  theory,  195 

Alcock,  168 

Alcohol,  117,  122 

Aldehydes,  130 

Aldo-hexose,  107 

Alice  springs,  69 

Alkali,  black,  74 

Alkali  cellulose,  124 

Alkali,  white,  74 

Alkaloids,  109,  152,  156 

Allantoin,  181 

Allotments,  208,  211 

Altitude,  65 

Aluminium,  72 

Alway,  84 

America,  22,  77,  136,  138 

Amide,  43,  109,  181 

Amines,  109 

Amino-acid,    34,  43,  51,   109,    149, 

180 

Ammonia,  13,  22,  109 
Ammonia,  sulphate  of,  11,  89,  175 
Ammonium  acetate,  182 
Ammonium  bi-carbonate,  18 
Ammonium  citrate,  31 
Ammonium  chloride,  17 
Ammonium  humate,  43 
Ammonium  hydrogen  carbonate,  18 
Ammonium  hydrogen  sulphate,  16 

D. 


Ammonium  hydrogen  sulphite,  16 

Ammonium  nitrate.  17 

Amoebae,  81,  91 

Amos,  26 

Amygdalin,  185 

Anaerobe,  50 

Analysis,  soil,  67,  78 

Annealing,  38,  131 

Anti-pepsin,  190 

Apatite,  25 

Apple,  104,  166,  167 

Appleyard,  85 

Apricot,  167 

Arabic,  gum,  106,  132 

Arabin,  132 

Arabinose,  132 

Arable  land,  211 

Arachidic  acid,  142 

Archbold,  133 

Argentine,  135 

Arginine,  149,  151,  152 

Argol,  104 

Armsby,  182 

Armstrong,  110,  190 

Armstrong  College,  221 

Artichoke,  108 

Ascensional  currents,  65 

Asparagine,  7,  109,  149,  181 

Aspartic  acid,  149,  151,  181,  182 

Aspect,  65 

Asphalte,  165 

Assam,  158 

Assimilation,  101,  188,  192 

Atlantic,  126 

Aubert,  133 

Auld,  146 

Australia,  30,  69,  132,  139,  170 

Available  lime,  28 

Available  nitrogen,  34,  81 

Available  phosphorus,  28,  87 

Available  plant  food,  4,  77 

Available  potash,  87 

Ayrshire  cow,  201 

BACHELOR  of  Science,  222 
Bacteria,  23,  27,  42,  50,  81 

15 


226 


INDEX 


Baden-Powell,  222 

Bailiffs,  221 

Bainbridge,  190 

Bajra,  125 

Balance  of  ingredients,  8,  64,  83 

Bald,  177 

Bales,  125,  126 

Balls,  84 

Baltic  linseed,  135 

Bamboo,  128 

Banana,  167 

Bank,  214,  215 

Barber,  133 

Bark,  162 

Barley,  12,  107,  124,  148,  171,  219 

Barley  straw,  12 

Barnes,  110 

Barrages,  95 

Barrenness,  93 

Basic  nitrogen  from  proteins,  149, 

152 
Basic  slag,  6, 16, 19,  20,  22,  27,  63,  67, 

97,  171,  174,  179,  203,  207,  216 
Basic  superphosphate,  31 
Bassia,  144 
Basu,  168 
Bayliss,  110 
Beans,  150,  168 
Beaven,  110 
Beccari,  147 
Bedding,  46 
Beech,  127 
Beech  leaf,  72 
Beech  mast,  57 
Beef,  197,  204 
Beer,  124 
Berries,  161,  167 
Berry,  133 
Bee<  103,  114,  128 
Beet  sugar,  107,  108,  114 
Bengal,  120,  126,  165 
Bennett,  32,  147,  162,  182,  224 
Benson,  134 

Benzamido  acetic  acid,  44 
Benzene,  181 
Bitter  cassava,  123 
Black  alkali,  74,  98 
Blackberry,  167 
Blackman,  92 
Back  cotton  seed,  125 
Black  soils,  66,  74,  96 
Blackwood,  90 
Blair,  146 

Blast  furnace  dust.  38,  39 
Blood,  23,  57,  179 
Boiled  oil,  136 
Boiler  flue  dust,  38 
Bombay,  69,  132,  143 
Bone,  32,  33 


Bone,  dissolved,  34 

Bone  phosphate,  32 

Bone,  vitriolated,  34 

Borax,  138 

Borday,  110 

Bottomley,  59 

Boulder  clay,  29,  78,  97,  203 

Boulton,  134 

Brazil,  162 

Bread,  118,  124,  147,  208,  219 

Brenchley,  85,  92 

Briggs,  134 

British  agricultural  workers,  216 

British  East  India  Company,  213 

British  Isles,  139 

Broad-casting,  6,  20,  26,  31 

Broadbalk,  Rothamsted,  26 

Bromides,  152 

Bromine,  124 

Browning,  146 

Brown  sugar,  113 

Buildings,  206,  210 

Bullock  Mill,  112 

Bullocks,  48,  178,  192,  197 

Burma,  120 

Burnett's  fluid,  127 

Burning  soil,  97 

Burnt  lime,  86 

Butter,  102,  137,  201,  211 

Buttercup,  174 

Butyrin,  199 

Byres,  206 

CABBAGES,  19,  175 

Caffeine,  156 

Calcareous  soil,  16,  72,  82,  163 

Calcium  acetate,  103,  130 

Calcium  bi-carbonate,  73,  86 

Calcium  carbide,  21,  88,  91 

Calcium  carbonate,  27,  73,  85,  86, 

168 

Calcium  citrate,  105 
Calcium  cyanamide,  21 
Calcium  hydrate,  27,  88 
Calcium  oxalate,  103 
Calcium  oxide,  27,  72,  86 
Calcium  silicate,  27 
Calcium  sulphate,    19,    51,    74,    89, 

104,  172,  177 
Calcium  sulphide,  87 
Calcium  sulphite,  91 
Calcutta,  143 
Calf  rearing,  137,  202,  218 
Calories,  191,  195,  198 
Calves,  48,  136,  137,  218 
Calving,  200 
Cambium,  164 
Cambridge  coprolites,  30 
Cameron,  224 


INDEX 


227 


Canada,  119 

Candles,  141 

Cane  sugar,  102,  107,  111,  174 

Cannabis  sativa,  127 

Canvas,  106 

Capillary  action,  67 

Capital,  210,  212,  222,  224 

Caramel,  113 

Carbide,  calcium,  21,  88,  91 

Carbohydrates,  102,  105,  111,  195 

Carbon  dioxide,  26,  73,  75,  85,  101, 

205 

Carbon  monoxide,  130 
Carbonic  acid,  26,  73,  75,  85,  87,  101 
Carding,  125 
Carey,  100 

Case-hardening,  38,  131 
Casein,  150,  199,  200 
Caseinogen,  150,  199,  200 
Casks,  20 
Cassava,  123 
Castor  bean,  151 
Castor  cake,  24,  112 
Catch  crops,  161,  223 
Catechin,  162 
Catechu,  162 
Cattle,  136,  142,  200 
Cellulose,  105,  124,  187,  193 
Centrifugal  machine,  113,  116 
Cereal  proteins,  147 
Cereals,  11,  40,  117,  118,  120,  124 
Cesspools,  54 
Ceylon,  144 
Chadwin,   133 

Chalk,  8, 24, 73, 85, 88,  88, 98, 103, 168 
Chamberlain,  224 
Chance  mud,  87 
Charcoal,  125,  129 
Cheese,  107,  197,  202,  211,  218 
Chemical  fumes,  168 
Chemistry,  soil,  70 
Chewing,  192,  193 
Children,  198 
Chili,  18 

China,  120,  132,  152,  158,  160 
Chlorides,  17,  108,  152,  168 
Chlorine,  108,  124 
Church,  133 
Cider,  104 
Cinchona,  153 
Cinchonin,  154 
Citric  acid,  28,  71,  77,  104 
Classification  of  fertilizers,  3 
Clay,  16,  19,  21,  40,  55,  64,  70,  82, 

96,  97,  203 
Clerks,  217 
Clifford,  58 
Close  packing,  62 
Clot,  Blood,  23 


Clouds,  65 

Clouston,  177,  223 

Clover  meal,  107 

Clovers,  25,  82,  98,  171,  172 

Coagulation,  clay,  87 

Coal,  11,  75 

Cockle  Park,  25,  29,  63,  66,  70,  81, 

171,  173,  179,  203,  204 
Coconuts,  131,  139 
Coffee,  19,  156,  160,  175 
Coir,  140 
Coke,  21 
Coke  ovens,  11 
Collins,  9 
Colloidal  clay,  89 
Colloids,  19,  44,  62,  64,  94,  106,  164, 

172 

Colonies,  207,  209 
Colophony,  145 
Colostrum,  200 
Colour  of  soils,  66 
Colza,  143 
Compact  soils,  66 
Composts,  57 

Compound  manures,  32,  40,  155 
Conduction  of  heat,  66 
Conifers,  127,  131 
Cooking  starch,  207 
Coombes,  malt,  124 
Coombs,  168 
Copeland,  146 
Copper,  104,  152 
Copper  hydrate,  109 
Copper  sulphate,  91 
Copra,  140 
Corn  manure,  40 
Cornwall,  132 
Corylin,  152 

Cotton,  105,  125,  137,  175 
Cotton  rags,  128 
Cotton- wool,  105 
Countess  Cinchon,  153 
Cousins,  224 
Coventry,  134 
Cows,  48,  183,  197,  201,  205 
Cracks  in  soil,  70 
Cranfield,  39 
Cream,  201 
Credit,  210 

Creosote,  127,  128,  164 
Crookes,  20 
Cross,  110,  134, 
Crowther,  146,  168,  198 
Crumb  structure,  62 
Crystallized  fruit,  167 
Cud, 193 
Culms,  124 

Cuprammonium  hydroxide,  105 
Cunningham,  222 


228 


INDEX 


Curd,  132,  199 

Currant,  168 

Currency,  214 

Custom,  215 

Cyanamide,  calcium,  10,  21 

Cyanides,  38,  88,  123,  136 

Cyanogenetic  glucoside,  123,  136 

Cystine,  151 

DAIRY,  197,  199 

Dams,  95 

Dark  soils,  66 

Dastoor,  215 

Date  palm,  116 

Davies,  168 

Davis,  134 

Davy,  Humphrey,  1,  9 

Day,  168 

Decorticated  rice,  121 

Decorticated  cotton  cake,  138 

Deep  rooting,  175 

Deep  tillage,  69 

Deflocculation  of  clay,  87 

Dehra  Dun,  158 

Delay  of  ripening.  10 

Deliquescence  of  fertilizers,  17,  19, 

20 

Den,  30 
Denbigh,  133 
Denitrification,  51,  82 
Depth  of  penetration  of  manures, 

7,  34 

Destructive  distillation,  125, 129,147 
Development  of  leaf,  17 
Dextrin,  106 
Dextrose,  106,  180 
Diabetes,  150 
Diastase,  106,  124 
Dibdin,  58 

Di-calcium  phosphate,  25,  31,  32 
Di-cyanamide,  22 
Diffusion  process,  114 
Di-gallic  acid,  163 
Digestion,  188,  194 
Dihydroxy  succinic  acid,  104 
Diminishing  returns,  83,  205.  216 
Di-saccharose,  107,  111 
Disease,  27,  73 
Dissolved  bones,  34 
Distillation,  destructive,   125,  129, 

147 

Distribution  of  fertilizers,  5,  7,  25 
Distributors,  manure,  25 
Dowling,  133 
Drage,  222 
Drainage,  16,  17,  19,  21,  45,  47,  52, 

68,  95,  183,  205 
Draughts,  206 
Dried  fruit,  167 


Driers  for  oil,  108,  136,  143 

Drill,  6,  21 

Drinking  coconuts,  139 

Drought,  7,  15,  21,  35,  95,  109,  110 

Drying  oil,  108,  136,  138,  143,  146 

Dry  lands,  94 

Dub  grass,  173 

Dung,  46,  192,  205 

Dunlop,  224 

Dunstan,  146 

Durham,  73,  178 

Dyer,  36,  77,  85,  104,  1 10,  133,  224 

Dyes,  125,  165 

EARTH  closet,  54 

Earth  nut,  142,  191 

Earths,  nitre,  21 

Earthworms,  5,  24 

East  Indian  rape,  143 

Eaton,  168 

Ebonite,  165 

Economy  of  water,  95,  101,  110 

Edestin,'l51 

Education,  220 

Efficiency  of  labour,  216 

Egypt,  21,  118,  125,  138 

Electric  carbon  filament,  106 

Electricity,  89,  92 

Elementary  nitrogen,  51,  82,  191 

Ellmore,  134 

Embryo,  149 

Emulsion,  128 

Enclosure,  moor,  98,  210 

Enzyme,  106,  136,  137,  159,  193 

Errors  of  experiment,  99 

Essential  oils,  109,  145 

Ester,  108 

Evans,  190 

Evaporation,  69,  95,  161,  180,  198 

Evolution  of  nitrogen,  51,  82 

Excreta,  47,  54,  188,  192 

Exhausted  soil,  3,  14,  86,  93 

Eyre,  146 

FABRIC,  125 

Faeces,  47,  54,  188,  192 

Farmyard  manure,  42,  52,  122,  173, 

179 

Fashions  in  farming,  83,  89 
Fat  stock,  183,  215 
Fats,  22,  33,  102, 108,  135,  179,  184, 

192 

Fattening,  192,  196 
Fatty  acids,  102,  108,141 
Faulty  buildings,  206,  210 
Feather  waste,  23 
Febrifuge,  154 
Feed  meal,  gluten,  120 
Fehling's  solution,  107,  108 


INDEX 


229 


Felling  timber,  127 

Fens,  96,  97 

Fenton,  110 

Fermentation,    50,    103,    117,    124, 

192 

Ferozepore,  143 
Ferric  hydrate,  26,  66,  71,  75 
Ferro  cyanide,  88 
Fertility,  2,  3,  67,  93,  169 
Fertilizers,  2,  10,  73,  86,  169 
Furfuraldehyde,  105 
Furfuroids,  106 
Fibres,  106,  125,  126 
Filter  paper,  105 
Financial  aspect,  211 
Fine  grinding,  6,  25,  41 
Finger  and  toe,  32,  73 
Fish,  22,  24,  158,  197 
Fisher,  146,  224,  1-97 
Fixation  of  atmospheric   nitrogen, 

11,  51,  81,82,  176,  203 
Fixation  of  fertilizer,  13 
Flax   126,  128,  135 
Flesh,  185,  192,  199 
Fletcher,  134 

Flocculation,  clay,  19,  74,  89,  96 
Florida  phosphate,  30 
Flour,  118.  122,  147,  207,  219 
Flour,  potato,  122,  219 
Fluff,  cotton,  125 
Fluorine,  25,  33 
Flush  of  tea,  158 
Fog,  65 

Foreign -grown  food,  219 
Forestry,  127,  215 
Formaldehyde,  101 
Formic  acid,  102 
Forster,   110 
Fowler,  58,  146,  168,  224 
Fream,  84,  223 
Free  selector,  170 
Fritsch,  224 
Frost,  91 
Fructose,  107,  108 
Fruit,  10,  163,  166,  175 
Fruit  sugar,  107 
Fungicides,  91 

GALACTOSE,  107,  108,  132,  199 

Gall  nuts,  163 

Gallo-tannic  acid,  163 

Gardens,  17,  54,  66,  122,  208,  211 

Garden  soils,  26,  54,  66 

Garrad,  157 

Gas,  wood,  129 

Gas  lime,  88,  91,  97 

Gasworks,  11,  18 

Gases  occluded  by  soils,  81 

Geerligs,  223 


Gel,  7,  44,  164 

Gelatine,  7,  32,  33 

Gelatinization,  starch,  106,  118,  207, 

219 

Gelose,  132 
Geranium,  wild,  174 
Germany,  37,  93,  214,  215 
Germicides,  91 
Germination  of  seeds,  38,  96 
Gilbert,  1,  76,  85,  195 
Gilchrist,  85,  179 
Gingelly,  144 
Gliadin,  147,  149 
Globulin,  150 
Glucose,  103,    106,    108,    123,    163, 

167,  186,  199 
Glucoside,  145,  185 
Glucosides,  cyanogenetic,  123,  136 
Glucosides,  nitrogenous,  109,  185 
Glue,  32 

Glutaminic  acid,  149,  151,  181 
Gluten,  147 

Gluten  feed  meal,  119,  120 
Glutenin,  147,  149 
Glycerine,  108,  141,  180,  184 
Glycogen,  187 
Goat,  202 
Gold  currency,  214 
Golding,  58 
Golf-green  worms,  24 
Gooseberries,  17,  19,  104 
Gorham,  100 
Gourlay,  222 
Gram  (pea),  125 
Grandeau,  76 
Grantham,  168 
Grape  sugar,  106 
Grapes,  104,  167 
Graphite,  21 

Grass,  124,  128,  173,  201,  203 
Grass   land,   29,    30,    63,    81,    179, 

211 

Grass  manure,  25,  40,  176 
Gravel  soil,  24,  66,  94,  160 
Gravity,  specific,  64,  199 
Grazing,  120,  179 
Green,  222 

Green  crop,  19,  119,  168,  175 
Greenhouses,  65,  90 
Greenwich,  67 
Gregory,  153 
Grigioni,  24 
Guano,  22,  35 
Guernsey,  cow,  201 
Gum,  106,  131,  132 
Guzerat,  143 
Gwilym  Williams,  157 
Gypsum,   19,    51,    74,  88,  96,  104, 

172,  177 


230 


INDEX 


HAAS,  110,  133,  224 

Hall,  9,  36,  84,  85,   133,  182,  203, 

210,  212,  222,  223 
Hanley,  92 
Hanson,  196 
Hard  pan,  19,  63 
Hard  woods,  127 
Hard  work  rations,  198 
Hardy,  157 
Harrowing,  66 
Haulms,  185 

Hay,  9, 12, 19, 124,  136, 171, 173,  201 
Haynes,  134 
Hazel  nuts,  152 
Heat,  soil,  65,  90 
Heather,  98 
Heavy  soils,  16,  19,  21,  40,  55,  64, 

70,  82,  96,  97,  203 
Hedge  clippings,  57 
Heidstam,  134 
Hemp,  127,  128,  145,  151 
Hendrick,  24,  59,  133 
Henry,  146 
Herring  waste,  22 
Hexoses,  106 
Higgins,  116,  133 
High  farming,  220 
High  prices,  220 
Hilgard,  84,  100,  224 
Hill,  110,  133,  182,  224 
Himalayan  rivers,  95 
Hindu  cultivation,  170 
Hippuric  acid,  44 
Histidine,  149,  152 
Hobsbaum,  24 
Hobson,  222 
Hoeing,  66,  116 
Holland  soil,  93 
Hollow  soil,  171 
Home-grown  food,  219 
Honey,  107 
Hoofs,  23 

Hoosfield,  Rothamsted,  26 
Hop  farmers,  24 
Hopkins,  224 
Hordein,  149 
Hormones,  181 
Horns,  23 

Horse  feeding,  48,  50,  183,  193 
Howard,  100,  133 
Hughes,  36 
Human  heat,  198 
Human  rations,  198 
Humic  acid,  43,  76 
Humogen,  58 
Humphry  Davy,  1,  9 
Humus,  16,  19,  21,  28,  42,  63,   70, 

76,  97 
Hutchinson,  81,  92 


Hydraulic  press,  125,  135 
Hydrochloric  acid,  32,  71,  168 
Hydrofluoric  acid,  71 
Hydrolysis,  124,  137,  143 
Hydroxy  propionic  acid,  103 
Hydroxy  succinic  acid,  104 
Hyland,  146 
Hysteresis,  164 

INDIA,  21,  47,  70,  94,  110,  111,  120, 
125,  126,  132,  135,  138,  143,  152, 
158,  165,  173,  207,  209,  213 

Indian  village,  214,  219 

Indiarubber,  163 

Indigo,   165 

Indigotin,  166 

Indo-Gangetic  alluvium,  78 

Indole,  181 

Industrial  farm,  178,  209,  210 

Infertile  soil,  14,  97 

Ingle,  224 

Insecticides,  154 

Insoluble  albuminoids,  7,  43,  147 

Insoluble  nitrogen,  34 

Insoluble  phosphates,  30,  34 

Intestinal  mucus,  188 

Intestines,  179,  184, 188,  193 

Iodine,  20,  106,  108,  152 

Iodine  value  of  oils,  136 

Ireland,  97,  126,  177,  218 

Irish  linen,  126 

Iron,  27,  66,  71,  74 

Irrigation,  66,  67,  94,  111,  118,  150 

Island,  Sea,  125 

Italy,  139 

JAM,  117,  167 

Japan,  120, 132, 138,151,158, 160,167 

Japanese  larch,  127 

Jatindra  Nath  Sen,  36 

Jersey  cow,  201 

Jesuit's  bark,  153 

Jethro  Tull,  1 

Johnson,  224 

Jones,  36 

Jorgensen,  90,  92,  110 

Joshi,  168 

luari,  125,  185 

Jute,  126 

KAINIT,  37 

Kangaroo,  170 

Keen,  84 

Kellner,  189,  196,  193,  196 

Kent  hops,  24 

Kernels,  rice,  121 

Kerry  cow,  201 

Kessel  Myer,  147 

Keto-hexose,  107 


INDEX 


231 


Kettle,  Linseed,  135 
Khair,  162 
Kidneys,  184 
Klason,  134 
Knapsack  sprayer,  168 
Knecht,  168 

LABOUR,  209,  210,  212,  215 

Lack  of  balance  in  soil,  8,  64,  83 

Lactation,  200 

Lactic  acid,  103 

Lactones,  103 

Lactose,  107,  199 

Laevulose,  107 

Lamb,  24 

Landowners,  220 

Latex,  164 

Laticiferous  system,  164 

Lawes,  1,  76,  85,  195 

Lawns,  145 

Lead,  136,  152 

Lead  acetate,  109,  152 

Lead-lined  tea  chests,  160 

Leaf  mould,  57 

Leake,  84 

Leather  (tanned),  35,  162 

Leather,  J.  W.,  85,  100, 133, 202,  224 

Leathes,  145,  190 

Leaves  as  litter,  45 

Leblanc,  87 

Leguminous  crops,  11,  27,  82,  150, 

172 

Leguminous  proteins,  150 
Lemons,  104 
Lemstiom,  90,  92 
Lentils,  150 
Lettuces,  175 
Light  soils,  40,  55 
Lignin,  106,  127,  129,  187 
Lime,  8,  14,  16,  19,  21    23    27,  28, 

72,  82,  86,  97,  113,  153,  165,  177, 

218 

Lime,  gas,  88 

Lime-magnesia  ratio,  9,  74 
Lime,  nitrate  of,  20 
Limestone,  86 
Linen,  126,  128,  135 
Linimarin,  123,  136,  185 
Linoleic  acid,  136 
Linseed,  24,  123,  126,  135,  143 
Linseed  cake,  7,  136,  183 
Linseed  mash,  137 
Litter,  44,  50 
Little  farms,  209 
Live  weight  increase,  204 
Lloyd,  146 

Loaf,  118,  124,  147,  207,  219 
Loam,  29,  78 
Lodging  of  crops,  10,  111 


Loewenthal,  168 

Logs,  127 

Long,  198 

Loose  packing  in  soil,  62 

Lubricating  oil,  144 

Luff,  168 

Luxmore,  78,  84 

Lying  in  bed,  calories,  198 

Lysine,  149,  151 

MACDONALD,  JAMES,  223 

Machinery,  210,  218 

Mackenzie,  133 

Maclennan,  92 

Madras,  78,  95,  142,  143,  162 

Magnesia,  8,  27,  33,  73,  86,  97,  158 

Maidment,  146,  198,  202 

Maintenance,  192,  198 

Maize,  119,  122,  148,  181 

Maize  germ  meal,  119 

Malic  acid,  104 

Malonic  acid,  104 

Malt,  106,  124,  171 

Malto-dextrin,  106 

Maltose,  106,  107 

Managers,  farm,  209 

Manchuria,  138 

Manganese,  8,  27,  72,  135 

Mangel  wurzel,  12,    114,    116,    171, 

175,   185,  201 
Manitoba  flour,  150 
Mann,  168 
Manure  heap,  43,  48 
Margarine,  141,  142,  144 
Market  garden,    17,   66,    122,    166, 

168,  211 
Marl,  97 

Marseilles  oil  extraction,  142,  144 
Marsh  gas,  188,  192 
Martineau,  133 
Maryland  soil,  93 
Matthai,  222 
Mauritius  sugar,  111 
Meadow  hay,  12,  19,  124,  136,  173, 

193,  201,  222 
Meal,  gluten  feed,  120 
Meal,  maize  germ,  119 
Meat,  waste,  24,  178,  206,  211,  213 
Mechanical  pulp,  128 
Mechanical  analysis  of  soil,  67 
Menzies,  190 
Mercerized  cotton,  125 
Meshes  of  sieves,  6,  25,  118 
Methyl  alcohol,  130 
Mica,  144 
Micro-coccus,  42 
Middleton,  179,  204,  222,  223 
Milk,  103,  105,  107,  197,  199,  206, 

211,  213 


232 


INDEX 


Milking  machines,  218 

Milk  sugar,  107,  199 

Miller,  85 

Millets,  125 

Millipedes,  91 

Mimosa,  163 

Mineral  phosphate,  30 

Mitchell,  146 

Mixed  farming,  178 

Mixed  fertilizer,  40 

Mixed  stock,  204 

Mohan,  202 

Moist  air,  19,  205 

Moisture,  19,  23.  65,  82 

Molasses,  113 

Money  (author),  168,  224 

Money  (cash),  212,  220 

Moneylenders,  219 

Mono-calcium  phosphate,  25,  31 

Mono-saccharose,  106 

Moors,  98,  210 

Mordanting,  103 

Morphine,  153 

Morrel,  146 

Morrison,  224 

Motor  ploughing,  208,  218 

Mowha,  24,  144 

Mowra,  144 

Mucilage,  131,  136,  187 

Mukerjee,  133,  224 

Mulch,  66,  68,  95,  111 

Muriate  of  ammonia,  17 

Muscle,  179 

Mustard  oil,  143 

Myer,  Kessel,  147 

Myrobalan,  162 

NAKED  cotton  seed,  125 

Naphthalene,  91 

Narcotine,  153 

New  land,  210 

Newsham,  223 

Nicol  prisms,  106 

Nicotine,  154 

Niger  seed,  1 44 

Night  soil,  54 

Nile,  94,  95 

Nitrate,  ammonium,  17 

Nitrate  of  lime,  17,  20 

Nitrate  of  potash,  21 

Nitrate  of  soda,  17,  18,  20,    21,  23, 

63,  87,  110,  171 

Nitrate,  soil,  51,  76,  80,  82,  109 
Nitre  earth,  21 
Nitre  well,  21 
Nitric  acid,  18,  21,  76 
Nitrification,  16, 22,  27,  51,  80,  82,  87 
Nitrifying  bacteria,  23,  91 
Nitrite,  51,  82 


Nitrogen,  10,  21,  22,  23,  47 
Nitrogen,  available,  13,  23,  87 
Nitrogen,  elementary,  51,  52 
Nitrogen  fixation,  51,  81,  82 
Nitrogen  in  feeding,  48 
Nitrogen  in  soil,  81 
Nitrogen  in  unripe  fodder,  110 
Nitrogenous    glucosides,    109,    123. 

126,  136,  185 

Nitrogenous  organic  manures,  22,  35 
Nitrous  acid,  51,  82 
Non-albuminoid  nitrogen,  109 
Norlin,  134 

North  American  maize,  119 
Northerly  aspect,  65 
Northern  counties,  208 
Northumberland,  67,78, 203, 209, 210 
Norway,  206 
Noyes,  222 
Nux  vomica,  156 
Nystron,  134 

OAK,  127,  162 

Oats,  12,  106,  171,  205,  219 

Occluded  gas,  81 

Offal,  22,  179 

Oil,  22,  108,  135,  184,  191 

Oils,  drying,  108,  136,  138,  143 

Oilseeds,  108,  117,  125,  135,  145 

Oil  substitutes,  136,  165 

Oil  theory  of  feeding,  195 

Okey,  134 

Old  village  sites,  21 

Oleic  acid,  108,  180 

Olive  oil,  137,  142,  144 

Oliver,  100 

Opium,  152 

Orange,  167 

Organic  matter  in  soil,  76 

Organic  nitrogen,  17,  22,  109 

Orr,  133 

Orwin,  133 

Osborne,  157 

O'Sullivan,  134 

Over-feeding  of  cows,  201 

Ox  feeding,  48,  178,  192,  197 

Oxalic  acid,  103 

Oxidation,  50,  51,  156 

Pacific  Island  phosphate,  30 
Packing  in  soils,  62 
Paddy,  120 
Palace  leas  hay,  173 
Palm  kernels,  139 
Palmitic  acid,  108,  180 
Palm  nuts,  139,  189 
Palm  sago,  123 
Pan,  hard,  19,  63 
Paper,  105,  128 


INDEX 


233 


Paramecia,  81,  91 

Parchment,  106,  161 

Paring  soils,  97 

Parmentier,  147 

Parry,  146 

Partial  sterilization,  90 

Pasture,  29,  30,  81,  173,  204,  210 

Peach,  167 

Pear,  167 

Peas,  150 

Peat,  7,  45,  58,  97,  128 

Peat  moss  litter,  45 

Pectins,  105,  187 

Pegler,  202 

Penetration,  5,  7,  31,  34 

Pentosans,  44,  105,  187 

Pentoses,  105,  187 

Peptones,  43,  50, 188 

Perchlorate,  potassium,  20 

Peru,  35,  153 

Pests,  soil,  90 

Petherbridge,  92 

Petroleum  spirit,  22,  33,  108,  136 

Philippines,  111 

Phlobaphenes,  163 

Phosphate,   7,   22,   25,   74,   77,   94, 

171,  174 

Phosphorus  in  animal,  49 
Phosphorus  in  fertilizers,  25,  27 
Phosphorus  in  soil,  26,  87,  94 
Photosphere  of  sun,  65 
Photo-synthesis,  101 
Physical  analysis  of  soil,  61,  67 
Physical  condition  of  soil,  29,  86 
Pickles,  103 

Pig,  23,  48,  55,  183,  196,  197 
Pig  iron,  27 
Pine  needles,  58 
Pine  trees,  127,  145 
Pith,  sago,  123 
Plant  food,  10,  93,  169 
Plimmer,  157,  190 
Ploughing,  60,  66,  208,  218 
Plum,  167 
Polar  regions,  2 
Pondicherry,  142 
Pool  retting,  126 
Poppy,  152 
Porritt,  168 

Postage  stamp  gum,  106 
Potash,  7,  22,  37,  74,  97, 126, 171, 174 
Potash,  available,  36,  77,  87 
Potash  manure,  37, 162 
Potassic  super-phosphate,  40 
Potassium  ferro-cyanide,  38 
Potassium  in  feeding,  48 
Potassium  hydrogen  tartrate,  104 
Potassium  iodate,  19 
Potassium  nitrate,  21 


Potassium  perchlorate,  19 

Potato,  12,  122,  151,  168,  171,  185, 

205 

Potato  eyes,  185 
Potato  flour,  122,  207,  219 
Potato  stalks,  128,  185 
Potato  starch,  106,  122,  207 
Potvliet,  133 
Poudrette,  54 
Poultry,  22,  56,  197 
Poverty  bottom,  98 
Prairie  soils,  3,  86 
Precipitated  chalk  spray,  168 
Preservatives  for  timber,  127 
Preservation  of  fruit,  167 
Priestley,  90,  92 
Primrose  McConnell,  100,  223 
Protein,  22,  109,  147,  185,  191 
Prussian  blue,  91 

Prussicacid,  123,  136,  137,  143,  185 
Pulp,  128,  161 
Pulses,  40,  150 
Punjab,  67,  118 
Pupils,  Agricultural,  210,  221 
Purgative,  181 
Purine,  181 
Pyridine,  181 
Pyrites,  71,  75,  165 
Pyro-ligneous  acid,  125,  130,  164 

QUEENSLAND,  111,  112 
Quicklime,  86 
Quinidine,  154 
Quinine,  154 

RAB  cultivation,  97 

Radiation,  2,65,  101,  198 

Raffinose,  107,  108 

Rag-bone,  33 

Rank  grass,  96 

Rape,  24,  143 

Raspberry,  167 

Ratio  C  to  N  in  soil,  77 

Ratio  of  labour  to  land,  219 

Ratio  of  lime  to  magnesia,  9,  73,  86 

Ratio  of  manure  to  land,  3,  40,  169, 

220 

Ratoon  crops,  111,  174 
Rawson,  168 

Re-afforestation,  127,  162,  215 
Reclamation,  92,  97,  100 
Red  beech,  72 
Red  hair,  72 
Red  soil,  66,  162 
Ren,  74,  96 
Rendering  oil,  108 
Resin,  145 
Retort  charcoal,  129 
Retting,  126 


234 


INDEX 


Reversion  of  plant  food,  31,  51 

Rhubarb,  103,  168 

Rice,  95,  120,  121,  208 

Ricin,  152 

Richards,  58 

Richmond,  202 

Rideal,  58,  110 

Ripening,  10,  17,  27,  175 

Road  sweepings,  67 

Roberts,  134 

Robertson,  36 

Roller,  use  of,  62,  69,  80 

Root  crops,  114,  116,  122,  151,  169 

Roots,  5,  26,  40,  62 

Ropes,  127,  143 

Roscoe,  92,  224 

Rosin,  145 

Rotation  of  crops,  119,  212 

Rotation  of  Jight,  108,  148 

Rothamsted,  1,  17,  69,  76,  83,  195 

Rotting,  50,  126 

Rouelle,  147 

Rowley,  134 

Rubber,  108,  136,  163,  209 

Rufisque,  142 

Ruminants,  187,  193 

Rural  industries,  215 

Rural  schools,  221 

Rushes,  128 

Russell,  24,  58,  81,  84,  92    133,  224 

Russian  linseed,  135,  136 

Ruston,  168 

Rye  grass,  12 

SACKING,  18,  126 

Safflower,  143 

Saffron,  143,  144 

Sago,  123 

Salad  oil,  142 

Sal  ammoniac,  17 

Salt,  common,  37,  116,  172,  180 

Sand,  39,  64,  71,  78,  94,  161 

Saponification,  108,  140 

Saponin,  24,  145 

Sardines,  142 

Sarson,  143 

Sawdust,  45,  103,  127,  129 

Scavenger,  54 

Scents,  145 

Schorlemmer,  92,  224 

Schreiner,  85 

Schryver,  134 

Scientific  training,  209 

Scotland,  soil,  93 

Scott,  24 

Scutching,  126 

Sea-bird  guano,  35 

Sea  Island  cotton,  125 

Sea  water,  37,  94,  140 


Seaweed,  57,  132 

Seeds,  38,  96,  108,  175 

Seeds,  hay,  173 

Senegal,  142 

Septic  tank,  56 

Sesame,  144 

Sewage,  54 

Sewage  farm,  55 

Shallow  tillage,  69,  94 

Sheep,  48,  178,  196,  197,  204 

Shell  lime,  86 

Shoddy,  23 

Short,  190 

Shortage  of  wheat,  20,  206 

Shorthorn  cows,  201 

Shrinkage  of  soils,  70 

Shrivell,  133 

Shutt,  157 

Sieve,  6,  25,  118 

Silk  waste,  23 

Silt,  100 

Silver,  acetate,  152 

Silvering  mirrors,  104 

Silver  skin,  161 

Simpson,  222 

Singling  turnips,  116 

Sirocco,  159 

Size  of  soil  particles,  61,  67,  78 

Skatole,  181 

Slag,  6,  8,  16,  20,  27,  63,  67,  97,  171, 

174,  179,  203,  208,  218 
Slaughter  house  waste,  23 
Slopes,  terraced,  120,  158,  161 
Sludge,  55 
Smetham,  222 
Smith,  134 
Snyder,  224 
Soap,  108,  140,  141,  142,  143,  144, 

145 

Soap  nut,  24,  145 
Sodium,  19,  74,  96 
Sodium  carbonate,  96 
Sodium  chloride,  37,  116,  172,  180 
Sodium  sulphate,  96 
Soil,  7,  60,  161 
Soil  improvement,  86 
Soil  nitrogen,  81 
Soil  pests,  90 
Soil  water,  68 
Solanin,  122,  185 
Solar  energy,  2,  65,  90,  101 
Solubility  of  fertilizers,  4,  10,  27,  34, 

41,  169 

Soluble  albuminoids,  7,  22,  147 
Soluble  nitrogen,  10,  34,  41 
Soluble  phosphate,  25,  34,  41 
Somerville,  98,  134,  179,  223 
Soot,  17,  66,  92 
Sorrel,  103 


INDEX 


235 


Souchida,  145 

Soudan  sudd,  128 

South  African  soya,  139 

South  America,  32,  139 

Southerly  aspect,  65 

South  Sea  Island  coconut,  139 

Sowing  seeds,  38,  92,  96 

Soy  bean,  138,  151 

Spain,  139 

Specific  gravity,  64,  199 

Specific  rotary  power,  108,  148 

Sprayer,  potato,  168 

Spring  wheat,  147 

Squatter,  Australian,  170 

Standard  sieve,  6,  25 

Starch,  102,  106,  117,  119,  121.  122, 

123,  124,  137,  186,  191,  207 
Starch  equivalent,  195 
Starch  gelatin ization,  106,  118,  207, 

219 

Steam  sterilization  of  soil,  90 
Stearic  acid,  108,  180,  184 
Stebbing,  134 

Steel  bomb  calorimeter,  191 
Steel,  by-products,  27 
Sterilization,  22,  90,  156 
Sterling,  168 
Stevens,  168 
Stiles,  110 
Stimulating  manures,  4,  11,  18,  20, 

31,  63,  169 
Stinging  nettles,  102 
St.  John,  202 
Stock,  live,  178 
Stokes,  100 

Stomach,  102,  188,  190,  193 
Stones,  61,  78 
Storage  of  manure,  50 
Store  beasts,  194 
Storer,  224 

Straw,  12,  45, 105, 126,  128,  136,  206 
Strawberry,  167 
Straw  gum,  105 
Straw  pulp,  128,  193 
Structure  of  soil,  61,  171 
Struggle  for  existence  among  plants, 

8 

Stachyose,  108 
Strychnine,  156 
Sub-soil,  19,  29,  60 
Succulent  crops,  17,  19,  175 
Sucrose,  27,  107,  111,  167,  186 
Sudd,  Soudan,  128 
Sugar,  27,  102,  111,  117,  167,  186 
Sugar  beet,  107,  108,  114- 
Sugarcane,  107,  111,  114,  174 
Sugar  refineries,  32,  116 
Sulphate  of  ammonia,  11,  40,   89, 
110,  119,  159,  162,  171,  175 


Sulphate  of  lime,  19,  51,  74,  75,  88, 

96,  104,  172,  177 
Sulphide,  calcium,  87 
Sulphite,  calcium,  91 
Sulphite  pulp,  128 
Sulpho-cyanide,  88 
Sulphur,  27,  75,  88,  89,  108,  165 
Sulphur  chloride,  108,  136 
Sulphur  dioxide,  16,  124,  128 
Sulphur  trioxide,  16 
Sulphuric  acid,  15,  75,  105,  136,  168 
Sun,  1,  65,  101 
Super-phosphate,  7,  12,  18,  19,  20, 

22,  30,  35,  97,  171,  177 
Supply  and  demand  of  plant  food, 

Supply  of  meat,  178,  207 

Surface  law  of  feeding,  194 

Surface  root,  35,  176 

Surface  washing,  soil,  7,  19 

Sussex  pasture,  67 

Sweated  labour,  217 

Swedes,   116,    151,    171,    176,    186, 

201 

Sweet  cassava,  123 
Symons,  146 
Synthetic  nitrogen  compounds,  11, 

20,  21 

TANKS,  Irrigation,  95 

Tannin,  162 

Tan  refuse,  45 

Tapioca,  123 

Tapping  trees,  145,  164 

Tar,  125,  127,  128,  129 

Tartar,  104 

Tartaric  acid,  104 

Tea,  156,  158,  161,  175 

Teaching,  agricultural,  221 

Tempany,  84 

Temperate  climates,  65 

Terracing  slopes,  120,  158,  161 

Tetra-calcium  phosphate,  25 

Tetra-saccharose,  108 

Textiles,  123,  125 

Theine,  156,  158,  160 

Thomson,  157 

Thorpe,  157,  223 

Thread,  125 

Tibbies,  224 

Tillage,  62,  69,  94,  211 

Til  seed,  144 

Timber,  125,  127,  129,  163,  215 

Titanium,  72 

Tobacco,  19,  21,  154 

Tom,  134 

Top  dressing,  4,  15,  18,  19,  20,  22, 

23,  31,  110,  119 
Town  stables,  50 


236 


INDEX 


Tree   Field,    Cockle   Park,    64,    81, 

173,  179 
Trees,  123,  125,  127,  129,  139,  153, 

163,  215 

Tri-calcium  phosphate,  25,  31,  32 
Tri-saccharose,  108 
Tropical  agriculture,  19,  54,  65,  95, 

111,  116,  119,  120,  123,  125,  139, 

153,  158 

Tryptophane,  151,  181 
Tull,  Jethro,  1 
Turnips,    19,    27,   30,    32,    69,    116, 

136,  183,  201 

Turnip  manure,  40,  116,  169 
Tumor,  221 
Turpentine,  109,  131,  145 

UNDERWOOD,  85 

United  States,  111,  112,  119,  139, 

170 

Unit  price,  41 

Universities  and  agriculture,  220 
Unsaturated  oils,  108 
Upper  Tyne,  205 
Uranium  acetate,  109 
Urea,  7,  42,  50,  191 
Uric  acid,  57,  181 
Urine,  44,  47,  57,  192 
Unripe  fruits,  163 
Usar,  74,  96 

VACUUM  pan,  113 

Vakil,  146 

Vanadium,  27 

Varnishes,   145 

Vegetable  cheese,  151 

Vegetarian  countries,  114 

Ventilation  of  cow  byres,  221 

Vetch,  151 

Vicilin,  150 

Vinegar,  103,  125,  129,  147 

Virgin  soils,  3,  60 

Vitriolated  bones,  34 

Voelcker,  1,  24,  58,  59,  146,  223 

Vorhees,  223 

Vulcanization,  136,  165 

WAGES,  agricultural,  214,  220 

Wallace,  133,  157 

Wanklyn,  190 

Warington,  84,  190,  202,  224 

Warner,  110 

Warping,  100 

Waste  animal  matter,  23 

Waste  lime,  87 


Waste  wood,  125,  129,  163 

Water,  2,  49,  95,  183 

Water  in  soil,  7,  62,  82,  110 

Water,  sewer,  55 

Watt,  134 

Wattle  gum,  132 

Wax,   108 

Wax  cloth,  144 

Weathering  of  soil,  61 

Weiss,  58 

Well  water,  21. 

Wentworth,  92 

Western  Ghats,  cultivation,  97 

West  Indies,  sugar,  111,  112 

Wet  lands,  95 

Whatnough,  157 

Wheat,  3,  12,  19,  20,  67,  105,  118, 

147,  150,  171,  191,  195 
Wheat  straw,  12,  105,  206 
Whey,  107 
Whitby,  168 
White  alkali,  74 
White  clover,  wild,  82,  172 
White  cotton  seed,  125 
White  crops,  118,  171 
White  rice,  121 
White  sugar,  113 
Wibberley,  223 
Wild  geranium,  174 
Wild  white  clover,  82,  172 
Wiley,  133,  223 
Willesden  paper,  106 
Williams,  Gwilym,  157 
Winter    application    of    fertilizers, 

16,  21,  23 
Winter  wheat,  147 
Wine,  104 
Wireworms,  91,  92 
Woburn,  19,  63 

Wood  (author),  133,  157,  182,  222 
Wood  (timber),  103,  125,  127,  128. 

129,  163,  215 
Wood  ash,  16,  37,  38 
Wood  tar,  128 
Wool  waste,  23 
Worms,  5,  24,  145 
Wright,  198,  223 
Wurzel,  mangel,  50,  114,  116 

YELLOW  plants,  15 
Yule,  182 

ZEIN,  148 

Zinc  chloride,  105,  106,  127,  128 

Zinc  oxide,  165 

Zinc  sulphate,  91 


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Barwise,  S.     The  Purification  of  Sewage i2mo,  3  50 

Baterden,  J.  R.     Timber.     (Westminster  Series.) 8\o,  *2  oo 

Bates,    E.    L.,    and    Charlesworth,    F.      Practical    Mathematics    and 

Geometry , i2mo, 

Part  I.    Preliminary  and  Elementary  Course *i  50 

Part  II.    Advanced  Course *i  50 

— —  Practical    Mathematics i2mo,  *2  oo 

—  Practical    Geometry    and    Graphics xamo,  2  oo 

Batey.  J.    The  Science  of  Works  Management. tamo,  *i  50 

—  Steam  Boilers  and  Combustion i2mo,  *i  50 

Bayonet  Training  Manual , i6mo,  o  30 

Beadle,  C.     Chapters  on  Papermaking.     Five  Volumes i2mo,  each,  *2  oo 

Beaumont,  R.     Color  in  Woven  Design 8vo,  *6  oo 

—  Finishing   of   Textile   Fabrics 8vo,  *7  50 

—  Standard  Cloths  8vo,  *y  50 

Beaumont,  W.  W.     The  Steam-Engine  Indicator 8vo,  2  50 

Eechhold,   H.     Colloids  in   Biology  and   Medicine.     Trans,   by  J.   G. 

Bullowa (In  Press.) 

Beckwith,  A.     Pottery 8vo,  paper,  o  60 

Bedell,  F.,  and  Pierce,  C.  A.    Direct  and  Alternating  Current  Manual. 

8vo,  2  oo 

Beech,  F.    Dyeing  of  Cotton  Fabrics 8vo,  7  50 

—  Dyeing   of  Woolen   Fabrics 8vo,  *4  25 

Begtrup,  J.     The  Slide  Valve 8vo,  *2  oo 

Beggs,  G.  E.    Stresses  in  Railway  Girders  and  Bridges (In  Press.} 

Bender,  C.  E.     Continuous  Bridges.     (Science  Series  No.  26.) i6mo,  o  50 

Proportions  of  Pins  used  in  Bridges.     (Science  Series  No.  4.) 

i6mo,  o  50 

Bengough,  G.  D.    Brass.     (Metallurgy  Series.) (In  Press.) 

Benne'tt,  H.  G.  The  Manufacture  of  Leather 8vo,  *5  oo 

Bernthsen,    A.      A  Text  -  book  of  Organic  Chemistry.      Trans,  by  G. 

M'Gowan    i2mo,  *s  oo 

Bersch,  J.     Manufacture  of  Mineral  and  Lake  Pigments.     Trans,  by  A.  C. 

Wright 8vo, 

Bertin,  L.  E.     Marine  Boilers.     Trans,  by  L.  S.  Robertson 8vo,  5  oo 

Beveridge,  J.     Papermaker's  Pocket  Book I2mo,  *4  oo 

Binnie,  Sir  A.    Rainfall  Reservoirs  and  Water  Supply 8vo,  *s  oo 

Binns,  C.  F.    Manual  of  Practical  Potting 8vo,  *io  oo 

The  Potter's  Craft ; i2mo,  *2  oo 

Birchmore,  W.  H.    Interpretation  of  Gas  Analysis I2mo,  *i  25 

Blaine,  R.  G.    The  Calculus  and  Its  Applications 12010,  *i  75 

Blake,  W.  H.    Brewers'  Vade  Mecum 8vo,  *4  oo 

Blanchard,  W.  M.    Laboratory  Exercises  in  General  Chemistry.  .i2mo,  i  oo 
Blasdale,  W.  C.     Quantitative  Chemical  Analysis.      (Van  Nostrand's 

Textbooks.)    i2mo,  *2  50 

Bligh,  W.  G.    The  Practical  Design  of  Irrigation  Works 8vo, 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  5 

Bloch,  L.     Science  of  Illumination.    Trans,  by  W.  C.  Clinton 8vo,  *2  50 

Blok,  A.     Illumination  and  Artificial   Lighting i2mo,  2  25 

Bliicher,  H.    Modern  Industrial  Chemistry.     Trans,  by  J.  P.  Millington. 

fcvo,  *7  50 

Blyth,  A.  W.    Foods:  Their  Composition  and  Analysis 8vo,  7  50 

Poisons:    Their  Effects  and  Detection 8vo,  8  50 

Bb'ckmann,    F.      Celluloid izmo,  *s  oo 

Bodmer,  G.  R.     Hydraulic  Motors  and  Turbines iimo,  5  oo 

Boileau,  J.  T.    Traverse  Tables 8vo,  5  oo 

Bonney,  G.  E.    The  Electro-platers'  Handbook i2mo,  i  50 

Booth,  N.     Guide  to  the  Ring-spinning  Frame i2mo,  *2  oo 

Booth,  W.  H.    Water  Softening  and  Treatment 8vo,  *2  50 

Superheaters  and  Superheating  and  Their  Control 8vo,  *i  50 

Bottcher,  A.     Cranes:   Their  Construction,  Mechanical  Equipment  and 

Working.     Trans,  by  A.  Tolhausen Ato,  *io  oo 

Bottler,  M.    Modern  Bleaching  Agents.    Trans,  by  C.  Salter. . .  .i2mo,  *3  oo 

Bottone,  S.  R.     Magnetos  for  Automobilists i2mo,  *i  oo 

—  Electro -Motors,  How  Made  and  How  Use i2mo,  i  oo 

Boulton,  S.  B.     Preservation  of  Timber.    (Science  Senes  No.  82.) .  i6mo,  o  50 

Bourcart,  E.     Insecticides,   Fungicides  and   Weedkillers 8vo,  *7  50 

Bourgougnon,  A.    Physical  Problems.    (Science  Series  No.  113.).  i6mo,  050 
Bourry,  E.     Treatise  on  Ceramic  Industries.     Trans,  by  A.  B.  Searle. 

8vo,  *7  25 

Bowie,  A.  J.,  Jr.    A  Practical  Treatise  on  Hydraulic  Mining 8vo,  5  oo 

Bowles,  O.    Tables  of  Common  Rocks.    (Science  Series  No.  125.). i6mo,  050 

Bowser,  E.  A.     Elementary  Treatise  on  Analytic  Geometry 12 mo,  i  75 

—  Elementary  Treatise  on  the  Differential  and  Integral  Calculus .  1 2mo,  2  25 

Elementary  Treatise  on  Analytic  Mechanics i2mo,  3  oo 

Elementary  Treatise  on  Hydro-mechanics i2mo,  2  50 

A  Treatise  on  Roofs  and  Bridges i2mo,  *2  25 

Boycott,  G.  W.  M.     Compressed  Air  Work  and  Diving 8vo,  *4  25 

Bradford,  G.,  2nd.    Whys  and  Wherefores  of  Navigation i2mo.  2  oo 

—  Sea  Terms  and  Phrases i2mo,  fabrikoid  (In  Press.) 

Bragg,  E.  M.     Marine  Engine  Design I2mo,  *2  oo 

Design  of  Marine  Engines  and  Auxiliaries 8vo,  *s  oo 

Brainard,  F.  R.     The  Sextant.     (Science  Series  No.  101.) i6mo, 

Brassey's   Naval  Annual   for   1915.     War  Edition 8vo,  A  oo 

Briggs,  R.,  and  Wolff,  A.  R.     Steam-Heating      (Science  Series  No. 

68. ) i6mo,  o  50 

Bright,  C.     The  Life  Story  of  Sir  Charles  Tilsoj  Bright 8vo,  *4  50 

—  Telegraphy,  Aeronautics  and  War 8vo,  6  oo 

Brislee,  T.  J.    Introduction  to  the  Study  of  Fuel.     (Outlines  of  Indus- 
trial Chemistry.) 8vo,  *3  oo 

Broadfoot,  S.  K.     Motors:  Secondary  Batteries.     (Installation  Manuals 

Series.) ismo,  *o  75 

Broughton,  H.  H.     Electric  Cranes  and  Hoists 

Brown,  G.    Healthy  Foundations.     (Science  Series  No.  80  ) i6mo,  ^o  50 

Brown,  H.     Irrigation 8vo,  *5  oo 

Brown,  H.    Rubber. 8vo,  *2  oo 

W.  A.     Portland  Cement  Industry 8vo,  3  oo 

Brown,    Wm.    N.      Dipping,    Burnishing,    Lacquering    and    Bronzing 

Brass  Ware   i2mo,  *2  oo 

Handbook   on  Japanning i2mo,  *2  50 


6          D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Brown,  Wm.  N.     The  Art  of  Enamelling  on  Metal i2mo,  *a  25 

House  Decorating  and  Painting i2mo,  *2  25 

. History  of  Decorative  Art i2mo,  *i  25 

Workshop   Wrinkles    8vo,  *i  75 

Browne,  C.  L.    Fitting  and  Erecting  of  Engines 8vo,  *i  50 

Browne,  R.  E.     Water  Meters.     (Science  Series  No.  81.) i6mo,  o  50 

Bruce,  E.  M.    Detection  of  Common  Food  Adulterants i2mo,  i  25 

Brunner,  R.     Manufacture  of  Lubricants,  Shoe  Polishes  and  Leather 

Dressings.     Trans,  by  C.  Salter 8vo,  *4  50 

Buel,  R.  H.     Safety  Valves.     (Science  Series  No.  21.) i6mo,  o  50 

Bunkley,  J.  W.     Military  and  Naval  Recognition  Book i6mo,  /  oc 

Burley,  G.  W.     Lathes,  Their  Construction  and  Operation i2mo,  2  25 

—  Machine  and  Fitting  Shop  Practice i2mo,  2  50 

—  Testing   of  Machine   Tools i2mo,  2  50 

Burnside,    W.     Bridge    Foundations i2mo,  *i  50 

Burstall,  F.  W.    Energy  Diagram  for  Gas.    With  Text 8vo,  i  50 

Diagram.     Sold  separately *i  oo 

Burt,  W.  A.    Key  to  the  Solar  Compass i6mo,  leather,  2  50 

Buskett,   E.   W.     Fire   Assaying i2mo,  *i  25 

Butler,   H.  J      Motor   Bodies   and   Chassis 8vo,  *3  oo 

Byers,  H.  G.,  and  Knight,  H.  G.     Notes  on  Qualitative  Analysis 8vo,  *i  50 

Cain,  W.     Brief  Course  ir  the  Calculus i2mo,  *i  75 

—  Elastic  Arches.     (Science  Series  No.  48.) i6mo,  o  50 

-—  Maximum  Stresses.     (Science  Series  No.  38.) i6mo,  o  50 

—  Practical  Designing  Retaining  of  Walls.     (Science  Series  No.  3.) 

i6mo,  o  50 

——Theory    of    Steel-concrete    Arches    and   of    Vaulted     Structures.  . 

(Science    Series    No.    42.) i6mo,  o  75 

Theory  of  Voussoir  Arches.     (Science  Series  No.  12.) i6mo,  o  50 

Symbolic  Algebra.     (Science  Series  No.  73.) . i6mo,  o  50 

Calvert,    G.    T.      The    Manufacture    of    Sulphate    of    Ammonia    and 

Crude  Ammonia   i2mo,  4  oo 

Carey,  A.  E.,  and  Oliver,  F.  W.     Tidal  Lands 8vo,  5  oo 

Carpenter,  F.  D.    Geographical  Surveying.    (Science  Series  No.  37.). i6mo, 

Carpenter,  R.  C.,  and  Diederichs,  H.     Internal  Combustion  Engines. .  8vo,  *5  oo 

Carter,  H.  A.     Ramie  (Rhea),  China  Grass i2mo,  *s  oo 

Carter,  H.  R.     Modern  Flax,  Hemp,  and  Jute  Spinning 8vo,  *4  50 

—  Bleaching,  Dyeing  and  Finishing  of  Fabrics 8vo,  *i  25 

Cary,  E.  R.     Solutiom  of  Railroad  Problems  with  the  Slide  Rule .  .  i6mo,  *i  oo 

Casler,  M.  D.    Simplified  Reinforced  Concrete  Mathematics 12 mo,  *i  oo 

Cathcart,  W.  L.     Machine  Design.     Part  I.  Fastenings 8vo,  *3  oo 

Cathcart,  W.  L.,  and  Chaff ee,  J.  I.     Elements  of  Graphic  Statics .  .  .8vo,  *3  oo 

—  Short  Course  in  Graphics i2mo,  i  50 

Caven,  R.  M.,  and  Lander,  G.  D.     Systematic  Inorganic  Chemistry. i2mo,  *2  oo 

Chalkley,  A.  P.     Diesel  Engines 8vo,  *4  oo 

Chalmers.  T.  W.     The  Production  and  Treatment  of  Vegetable  Oils, 

4to,  7  50 

Chambers'  Mathematical  Tables 8vo,  i  75 

Chambers,  G.  F.     Astronomy •. i6mo,  *i  50 

Chappel,  E.    Five  Figure  Mathematical  Tables 8vo,  *2  oo 

Charnock,    Mechanical    Technology 8vo,  *s  oo 

Charpentier,    P.     Timber 8vo,  *7  25 

Chatley,  H.     Principles  and  Designs  of  Aeroplanes.     (Science  Series 

No.  126) i6mo,  o  50 

How  to  Use  Water  Power i2mo,  *i  50 

Gyrostatic  Balancing    8vo,  *i  25 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG          7 

Child,  C.  D.    Electric  Arc 8vo,  *2  oo 

Christian,    M.      Disinfection    and    Disinfectants.      Trans,    by    Chas. 

Salter i2mo,  300 

Christie,  W.  W.     Boiler-waters,  Scale,  Corrosion,  Foaming 8vo,  *3  oo 

—  Chimney  Design  and  Theory 8vo,  *3  oo 

Furnace  Draft.     (Science  Series  No.  123.) i6mo,  o  50 

—  Water :  Its  Purification  and  Use  in  the  Industries 8vo,  *2  o  o 

Church's  Laboratory  Guide.    Rewritten  by  Edward  Kinch 8vo,  *i  50 

Clapham,  J.  H.     Woolen  and  Worsted  Industries 8vo,  2  oo 

Clapperton,  G.     Practical  Papermaking 8vo,  2  50 

Clark,  A.  G.     Motor  Car  Engineering. 

Vol.    I.     Construction *4  oo 

Vol.  II.     Design 8vo,  *3  oo 

Clark,  C.  H.     Marine  Gas  Engines.     New  Edition 2  oo 

Clark,  J.  M.     New  System  of  Laying  Out  Railway  Turnouts i2mo,  i  oo 

Clarke,  J.  W.,  and  Scott,  W.    Plumbing  Practice. 

Vol.      I.     Lead  Working  and  Plumbers'  Materials 8vo,  *4  oo 

Vol.    II.    Sanitary  Plumbing  and  Fittings. (In  Press.} 

Vol.  III.     Practical  Lead  Working  on  Roofs (In  Press.) 

Clarkson,  R.  B.     Elementary  Electrical  Engineering (In  Press.} 

Clausen-Thue,  W.     A  B   C   Universal  Commercial   Telegraphic   Code. 

Sixth  Edition (In  Press.) 

Clerk,  D.,  and  Idell,  F.  E.     Theory  of  the  Gas  Engine.     (Science  Series 

No.  62.) i6mo,  o  50 

Clevenger,  S.  R.     Treatise  on  the  Method  of  Government  Surveying. 

i6mo,   morocco,  2  50 

Clouth,  F.     Rubber,  Gutta-Percha,  and  Balata, 8vo,  *6  oo 

Cochran,  J.    Concrete  and  Reinforced  Concrete  Specifications 8vo,  *2  50 

Inspection  of  Concrete  Construction 8vo,  *4  oo 

-  Treatise  on  Cement  Specifications 8vo,  *i  oo 

Cocking,  W.  C.     Calculations  for  Steel-Frame  Structures t2mc,  *s  oo 

Coffin,  J.  H.  C.   Navigation  and  Nautical  Astronomy.  i2mo  (In  Prcs?) 
Colburn,  Z.,  and  Thurston,  R.  H.     Steam  Boiler  Explosions.     (Science 

Series  No.  2.) i6mo,  o  50 

Cole,  R.  S.     Treatise  on  Photographic  Optics i2mo,  i  50 

Coles-Finch,  W.     Water,  Its  Origin  and  Use 8vo,  *5  oo 

Collins,  C.  D.    Drafting  Room  Methods,  Standards  and  Forms 8vo,  2  oo 

Collins,  J.  E.    Useful  Alloys  and  Memoranda  for  Goldsmiths,  Jewelers. 

i6mo,  o  50 

Collis,  A.  G.     High  and  Low  Tendon  Switch-Gear  Design 8vo,  *3  50 

Switchgear.      (Installation    Manuals   Series.) i2mo,  *o  50 

Colver,  E.  D.  S      High  Explosives 8vo,  20  oo 

Comstock,  D.  F.,  and  Troland,  L.  T.     The  Nature  of  Electricity  and. 

Matter 8vo,  *2  oo 

Coombs,  H.  A.     Gear  Teeth.     (Science  Series  No.  120.) i6mo,  o  50 

Cooper,  W.  R.     Primary  Batteries 8vo,  *6  oo 

Copperthwaite,  W.  C.     Tunnel  Shields 4to,  *g  oo 

Corfield,  W.  H.     Dwelling  Houses.     (Science  Series  No.  50.) i6mo,  o  50 

Water  and  Water-Supply.     (Science  Series  No.  17.) i6mo,  o  50 

Cornwall,  H.  B.    Manual  of  Blow-oipe  Analysis 8vo,  *2  50 

Cowee,  G.  A.    Practical  Safety  Methods  and  Devices 8vo,  *3  oo 


8          D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Cowell,  W.  B.     Pure  Air,  Ozone,  and  Water tamo,  *3  oo 

Craig,  J.  W.,  and  Woodward,  W.  P.     Questions  and  Answers  About 

Electrical   Apparatus i2mo,  leather,  i  50 

Craig,  T.     Motion  of  a  Solid  in  a  Fuel.     (Science  Series  No.  49.) .  i6mo,  o  50 

Wave  and  Vortex  Motion.     (Science  Series  No.  43.) i6rno,  o  50 

Cramp,  W.     Continuous  Current  Machine  Design 8vo,  *2  50- 

Crehore,  A.  C.     Mystery  of  Matter  and  Energy ..8vo,  i  oo 

Greedy,  F.     Single  Phase  Commutator  Motors 8vo,  *2  oo- 

Crocker,  F.  B.    Electric  Lighting.    Two  Volumes.    8vo. 

Vol.   I.    The  Generating  Plant 3  o> 

Vol.  n.    Distributing  Systems  and  Lamps 

Crocker,  F.  B.,  and  Arendt,  M.    Electric  Motors 8vo,  *2  50 

Crocker,  F.  B.,  and  Wheeler,  S.  S.    The  Management  of  Electrical  Ma- 
chinery   i2mo,  *i  oo 

Crosby,  E.  U.,  Fiske,  H.  A.,  and  Forster,  H.  W.     Handbook  of  Fire 

Protection 12010,  4  oo 

Cross,  C.  F.,  Bevan,  E.  J.,  and  Sindall,  R.  W.    Wood  Pulp  and  Its  Applica- 
tions.    (Westminster  Series.) 8vo,  *2  oo 

Crosskey,  L.  R.     Elementary  Perspective.. 8vo,  i  25 

Crosskey,  L.  R.,  and  Thaw,  J.    Advanced  Perspective 8vo,  i  50 

Culley,  J.  L.    Theory  of  Arches.     (Science  Series  No.  87.) i6mo,  o  50 

Cushing,  H.  C.,  Jr.,  and  Harrison,  N.    Central  Station  Management.  ..  *2  oo 

Dadourian,  H.  M.    Analytical  Mechanics i2mo,  *3  oo 

Dana,  R.  T.    Handbook  of  Construction  plant i2mo,  leather,  *s  oo 

Danby,  A.     Natural  Rock  Asphalts  and  Bitumens 8vo,  *2  50 

Davenport,  C.     The  Book.     (Westminster  Series.) 8vo,  *2  oo 

Davey,  N.    The  Gas  Turbine 8vo,  *4  oo 

Davies,  F.  H.    Electric  Power  and  Traction 8vo,  *2  oo 

—  Foundations  and  Machinery  Fixing.     (Installation  Manual  Series.) 

i6mo,  *i  oo 

Deerr,  N.     Sugar  Cane 8vo,  9  oo 

Deite,  C.    Manual  of  Soapmaking.    Trans,  by  S.  T.  King 4to, 

De  la  Coux,  H.  The  Industrial  Uses  of  Water.  Trans,  by  A.  Morris. Svo,  *6  oo 

Del  Mar,  W.  A.    Electric  Power  Conductors Svo,  *2  oo 

Denny,  G.  A.    Deep-level  Mines  of  the  Rand 4to,  *io  oo 

Diamond  Drilling  for  Gold *5  oo 

De  Roos,  J.  D.  C.     Linkages.     (Science  Series  No.  47.) i6mo,  o  50 

Derr,  W.  L.    Block  Signal  Operation Oblong  i2mo,  *i  50 

Maintenance-of-Way  Engineering (In  Preparation.) 

Desaint,  A.    Three  Hundred  Shades  and  How  to  Mix  Them Svo,  *io  oo 

De  Varona,  A.     Sewer  Gases.     (Science  Series  No.  55.) i6mo,  o  50 

Devey,  R.  G.    Mill  and  Factory  Wiring.     (Installation  Manuals  Series.) 

i2mo,  *i  oo 

Dibdin,  W.  J.     Purification  of  Sewage  and  Water Svo,  6  50 

Dichmann,  Carl.     Basic  Open-Hearth  Steel  Process 12 mo,  *3  50 

Dieterich,  K.     Analysis  of  Resins,  Balsams,  and  Gum  Resins. ..  .Svo,  *s  75 

Dilworth,  E.  C.    Steel  Railway  Bridges 4to.  *4  oo 

Dinger,  Lieut.  H.  C.    Care  and  Operation  of  Naval  Machinery. .  .i2mo,  *s  oo 
Dixon,  D.  B.     Machinist's  and  Steam  Engineer's  Practical  Calculator. 

i6mo,  morocco,  i  25 
Dodge,  G.  F.    Diagrams  for  Designing  Reinforced  Concrete  Structures, 

folio,  *4  oo 

Dommett,  W.  E.    Motor  Car  Mechanism i2mo,  *2  25 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  9 

Dorr,  B.  F.     The  Surveyor's  Guide  and  Pocket  Table-book. 

i6mo,  morocco,  2  oo 

Draper,  C.  H.    Elementary  Text-book  of  Light,  Heat  and  Sound .  .  12 mo,  i  oo 

—  Heat  and  the  Principles  of  Thermo-dynamics i2mo,  *2  oo 

Draper,   E.  G.     Navigating  the   Ship i2mo,  i  50 

Dron,  R.  W.     Mining  Formulas i2mo,  i  oo 

Dubbel,  H.    High  Power  Gas  Engines 8vo,  *5  oo 

Dumesny,  P.,  and  Noyer,  J.     Wood  Products,  Distillates,  and  Extracts. 

8vo,  *6  25 
Duncan,  W.  G.,  and  Penman,  D.     The  Electrical  Equipment  of  Collieries. 

8vo,  *6  75 

Dunkley,  W.  G.    Design  of  Machine  Elements.  Two  Volumes. 8vo,  each,  2  50 
Dunstan,  A.  E.,  and  Thole,  F.  B.  T.     Textbook  of  Practical  Chemistry. 

i2mo,  *i  40 

Durham,  H.  W.     Saws 8vo,  2  50 

Duthie,  A.  L.     Decorative  Glass. Processes.     (Westminster  Series.)  .8vo,  *2  oo 

Dwight,  H.  B.     Transmission  Line  Formulas 8vo,  *2  oo 

Dyson,  S.  S.     Practical  Testing  of  Raw  Materials 8vo,  *5  oo 

Dyson,  S.  S.,  and  Clarkson,  S.  S.     Chemical  Works 8vo,  *n  50 

Eccles,  W.  H.     Wireless  Telegraphy  and  Telephony i2mo,  *8  80 

Eck,  J.     Light,  Radiation  and  Illumination.     Trans,  by  Paul  Hogner, 

8vo,  *2  50 

Eddy,  H.  T.    Maximum  Stresses  under  Concentrated  Loads 8vo,  i  50 

Eddy,  L.  C.     Laboratory  Manual  of  Alternating  Currents i2mo,  o  50 

Edelman,  P.  Inventions  and  Patents i2mo,  *i  50 

Edgcumbe,  K.     Industrial  Electrical  Measuring  Instruments 8vo, 

(In  Press.) 

Edler,  R.     Switches  and  Switchgear.     Trans,  by  Ph.  Laubach .  . .  8vo,  *4  oo 

Eissler,  M.     The  Metallurgy  of  Gold 8vo,  9  oo 

The  Metallurgy  of  Silver 8vo,  4  oo 

—  The   Metallurgy  of  Argentiferous   Lead 8vo,  6  25 

A  Handbook  on  Modern  Explosives 8vo,  5  oo 

Ekin,  T.  C.    Water  Pipe  and  Sewage  Discharge  Diagrams folio,  *3  oo 

Electric  Light  Carbons,  Manufacture  of 8vo,  i  oo 

Eliot,  C.  W.,  and  Storer,  F.  H.     Compendious  Manual  of  Qualitative 

Chemical  Analysis i2mo,  *i  25 

Ellis,  C.     Hydrogenation  of  Oils 8vo,  7  50 

.Ultraviolet   Li^ht,  Its   Applications  in   Chemical   Arts lamo, 

(In  Prpsrt 

Ellis,  G.     Modern  Technical  Drawing 8vo,  *2  oo 

Ennis,  Wm.  D.     Linseed  Oil  and  Other  Seed  Oils 8vo,  *4  oo 

Applied  Thermodynamics , 8vo,  *4  50 

Flying  Machines  To-day I2mo,  *i  50 

Vapors  for  Heat  Engines i2mo,  *i  oo 

Ermen,  W.  F.  A.     Materials  Used  in  Sizing 8vo,  *2  oo 

Erwin,  M.     The  Universe  and  the  Atom i2mo,  *2  oo 

Evans,  C.  A.     Macadamized  Roads (In  Press.) 

Ewing,  A.  J,    Magnetic  Induction  in  Iron 8vo,  *4  oo 

Fairchild,  J.  F.    Graphical  Compass  Conversion  Chart  and  Tables...  o  50 

Fairie,  J.     Notes  on  Lead  Ores i2mo,  *o  50 

Notes  on  Pottery  Clays i2mo,  *2  25 


10       D.  V-  N  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Fairley,  W.,  and  Andre,  Geo.  J.    Ventilation  of  Coal  Mines.     (Science 

Series  No.  58.) i6mo,  o  50 

Fairweather,  W.  C.    Foreign  and  Colonial  Patent  Laws 8vo,  *3  oo 

Falk,  M.  S.     Cement  Mortars  and  Concretes • 8vo,  *2  50 

Fanning,  J.  T.     Hydraulic  and  Water-supply  Engineering 8vo,  *s  oo 

Fay,  I.  W.    The  Coal-tar  Colors 8vo,  *4  oo 

Fernbach,  R.  L.     Glue  and  Gelatine 8vo,  *3  oo 

Findlay,  A.    The  Treasures  of  Coal  Tar i2mo,  2  oo 

Firth,  J.  B.    Practical  Physical  Chemistry i2mo,  i  25 

Fischer,  E.    The  Preparation  of  Organic  Compounds.    Trans,  by  R.  V. 

Stanford i2mo,  *i  25 

Fish,  J.  C.  L.    Lettering  of  Working  Drawings Oblong  8vo,  i  oo 

Mathematics  of  the  Paper  Location  of  a  Railroad,  .paper,  i2mo,  *o  25 

Fisher,  H.  K.  C.,  and  Darby,  W.  C.     Submarine  Cable  Testing 8vo,  *3  50 

Fleischmann,  W.    The  Book  of  the  Dairy.    Trans,  by  C.  M.  Aikman. 

8vo,  4  50 
Fleming,  J.  A.     The  Alternate-current  Transformer.    Two  Volumes.  8vo. 

Vol.    I.     The  Induction  of  Electric  Currents *5  50 

Vol.  II.    The  Utilization  of  Induced  Currents 5  50 

Propagation  of  Electric  Currents , 8vo,  *$  oo 

A  Handbook  for  the  Electrical  Laboratory  and  Testing  Room.    Two 

Volumes 8vo,  each,  *6  50 

Fleury,  P.     Preparation  and  Uses  of  White  Zinc   Paints 8vo,  *$  50 

Flynn,  P.  J.    Flow  of  Water.     (Science  Series  No.  84.) i2mo,  o  50 

Hydraulic  Tables.     (Science  Series  No.  66.) i6mo,  o  50 

Forgie,  J.     Shield  Tunneling 8vo.    (In  Press.) 

Foster,  H.  A.    Electrical  Engineers'  Pocket-book.     (Seventh  Edition.) 

i2mo,  leather,  5  oo 

• Engineering  Valuation  of  Public  Utilities  and  Factories  . 8vo,  *3  oo 

Handbook  of  Electrical  Cost  Data 8vo  (In  Press.) 

Fowle,  F.  F.     Overhead  Transmission  Line  Crossings i2mo,  *i  50 

The  Solution  of  Alternating  Current  Problems 8vo  (In  Press.) 

Fox,  W.  G.     Transition  Curves.  '  (Science  Series  No.  no.) i6mo,  o  50 

Fox,  W.,  and  Thomas,  C.  W.    Practical  Course  in  Mechanical  Draw- 
ing   i2mo,  i  25 

Foye,  J.  C.     Chemical  Problems.     (Science  Series  No.  69.) i6mo,  o  50 

Handbook  of  Mineralogy.     (Science  Series  No.  86.) i6mo,  o  50 

Francis,  J.  B.     Lowell  Hydraulic  Experiments 4to,  15  oo 

Franzen,  H.     Exercises  in  Gas  Analysis i2mo,  *i  oo 

Freudemacher,  P.   W.    Electrical   Mining  Installations.     (Installation 

Manuals  Series.) i2mo,  *i  oo 

Friend,  J.  N.     The  Chemistry  of  Linseed  Oil i2mo,  i  oo 

Frith,  J.     Alternating  Current  Design 8vo,  *2  50 

Fritsch,  J.    Manufacture  of  Chemical  Manures.    Trans,  by  D.  Grant. 

8vo,  *6  50 

Frye,  A.  I.     Civil  Engineers'  Pocket-book i2mo,  leather,  *5  oo 

Fuller,  G.  W.    Investigations  into  the  Purification  of  the  Ohio  River. 

4to,  *io  oo 
Furnell,  J.    Paints,  Colors,  Oils,  and  Varnishes 8vo. 

Gairdner,  J.  W.  I.    Earthwork 8vo  (In  Press.) 

Gant,  L.  W.    Elements  of  Electric  Traction 8vo,  *2  50 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  n 

Garcia,  A.  J.  R.  V.     Spanish-English  Railway  Terms 8vo,  *4  50 

Gardner,  H.  A.     Paint  Researches,  and  Their  Practical  Applications, 

8vo,  *s  oo 
Garforth,  W.  E.     Rules  for  Recovering  Coal  Mines  after  Explosions  and 

Fires i2mo,  leather,  i  50 

Garrard,  C.  C.    Electric  Switch  and  Controlling  Gear 8vo,  *6  oo 

Gaudard,  J.     Foundations.     (Science  Series  No.  34.) i6mo,  050 

Gear,  H.  B.,  and  Williams,  P.  F.     Electric  Central  Station  Distribution 

Systems    8vo,  *3  50 

Geerligs,  H.  C.  P.     Cane  Sugar  and  Its  Manufacture 8vo,  •  *6  oo 

—  Chemical  Control  in  Cane  Sugar  Factories 4to,  5  oo 

Geikie,  J.     Structural  and  Field  Geology 8vo,  *4  oo 

Mountains.     Their   Growth,   Origin  and   Decay 8vo,  *4  oo 

—  The  Antiquity  of  Man  in  Europe 8vo,  *s  oo 

Georgi,  F.,  and  Schubert,  A.     Sheet  Metal  Working.     Trans,  by  C. 

Salter 8vo,  4  25 

Gerhard,  W.  P.  Sanitation,  Watersupply  and  Sewage  Disposal  of  Country 

Houses i2mo,  *2  oo 

Gas  Lighting  (Science  Series  No.  in.) i6mo,  o  50 

Household  Wastes.  (Science  Series  No.  97.) i6mo,  o  50 

—  House  Drainage.     (Science  Series  No.  63.) i6mo,  o  50 

Sanitary  Drainage  of  Buildings.     (Science  Series  No.  93.)           i6mo,  o  50 

Gerhardi,  C.  W.  H.    Electricity  Meters 8vo,  *6  oo 

Geschwind,   L.     Manufacture   of   Alum   and   Sulphates.     Trans,    by   C. 

Salter 8vo,  *s  oo 

Gibbings,  A.  H.     Oil  Fuel  Equipment  for  Locomotives 8vo,  *a  50 

Gibbs,  W.  E.     Lighting  by  Acetylene i2mo,  *i  50 

Gibson,  A.  H.     Hydraulics  and  Its  Application 8vo,  *5  oo 

-  Water  Hammer  in  Hydraulic  Pipe  Lines i2mo,  *2  oo 

Gibson,  A.  H.,  and  Ritchie,  E.  G.    Circular  Arc  Bow  Girder 4to,  *3  50 

Gilbreth,  F.  B.     Motion  Study I2mo,  *2  oo 

Bricklaying  System    8vo,  *3  oo 

Field  System  i2mo,  leather,  *3  oo 

Primer  of  Scientific  Management i2mo,  *i  oo 

Gillette,  H.  P.    Handbook  of  Cost  Data i2mo,  leather,  *s  oo 

Rock  Excavation  Methods  and  Cost i2mo,  *s  oo 

and  Dana,  R.  T.    Cost  Keeping  and  Management  Engineering .  8vo,  *s  50 

and  Hill,  C.  S.    Concrete  Construction,  Methods  and  Cost.  ..  .8vo,  *s  oo 

Gillmore,  Gen.  Q.  A.    Roads,  Streets,  and  Pavements i2mo,  i  25 

Godfrey,  E.     Tables  for  Structural  Engineers i6mo,  leather,  *2  50 

Goldinf ,  H.  A.     The  Theta-Phi  Diagram i2mo,  *2  oo 

Goldschmidt,  R.  Alternating  Current  Commutator  Motor 8vo,  *3  oo 

Goodchild,  W.  Precious  Stones.  (Westminster  Series.) .  8vo,  *2  oo 

Goodell,  J.  M.  The  Location,  Construction  and  Maintenance  of 

Roads 8vo,  i  50 

Goodeve,  T.  M.  Textbook  on  the  Steam-engine i2tno,  2  oo 

Gore.  G.  Electrolytic  Separation  of  Metals 8vo,  *3  50 

Gould,  E.  S.  Arithmetic  of  the  Steam-engine 12 mo,  i  oo 

Calculus.  (Science  Series  No.  112.) i6mo,  o  50 

— —  High  Masonry  Dams.  (Science  Series  No.  22.) i6mo,  o  50 

Gould,  E.  S.  Practical  Hydrostatics  and  Hydrostatic  Formulas.  (Science 

Series  No,  117.) i6mo,  o  50 


12        D.  VAN  NOSTRAND  CO/S  SHORT  TITLE  CATALOG 

Gratacap,  L.  P.    A  Popular  Guide  to  Minerals 8vo,  *2  oo 

Gray,  J.     Electrical  Influence  Machines 12010,  2  oo 

Marine  Boiler  Design I2mo,  *i  25 

Greenhill,  G.     Dynamics  of  Mechanical  Flight 8vo,  *2  50 

Gregorius,  R.     Mineral  Waxes.     Trans,  by  C.  Salter i2mo,  *s  50 

Grierson,  R.     Some  Modern  Methods  of  Ventilation 8vo,  *s  oo 

Griffiths,  A.  B.     A  Treatise  on  Manures i2mo,  3  oo 

Dental    Metallurgy    8vo,  *4  25 

Gross,  E.     Hops 8vo,  *6  25 

Grossman,  J.     Ammonia  and  Its  Compounds i2mo,  *i  25 

Groth,  L.  A.     Welding  and  Cutting  Metals  by  Gases  or  Electricity. 

(Westminster  Series) Svo,  *2  oo 

Grover,  F.     Modern  Gas  and  Oil   Engines 8vo,  *s  oo 

Gruner,  A.     Power-loom  Weaving 8vo,  *3  oo 

Grunsky,  C.  E.     Topographic  Stadia  Surveying i6mo,  2  oo 

Giildner,  Hugo.     Internal  Combustion  Engines.     Trans,  by  H.  Diederichs. 

4to,  *is  oo 

Anther,  C.  0.     Integration Svo,  *i  25 

Guraen,  Ii.  L.     Traverse  Tables folio,  half  morocco,  *7  50 

Guy,  A.  E.     Experiments  on  the  Flexure  of  Beams 8vo,  *i  25 

Haenig,   A.     Emery   and   Emery   Industry 8vo,  *3  oo 

Hainbach,  R.     Pottery  Decoration.    Trans.,  by  C.  Salter i2mo,  *4  25 

Hale,  W.  J.    Calculations  of  General  Chemistry. i2mo,  *i  25 

Hall,  C.  H.     Chemistry  of  Paints  and  Paint  Vehicles i2mo,  *2  oo 

Hall,  G.  L.    Elementary  Theory  of  Alternate  Current  Working ....  Svo, 

Hall,  R.  H.     Governors  and  Governing  Mechanism i2mo,  *2  50 

Hall,  W.  S.     Elements  of  the  Differential  and  Integral  Calculus Svo,  *2  25 

Descriptive  Geometry Svo  volume  and  a  4to  atlas,  *3  50 

Haller,  G.  F.,  and  Cunningham,  E.  T.     The  Tesla  Coil i2mo,  *i  25 

Halsey,  F.  A.     Slide  Valve  Gears i2mo,  i  50 

The  Use  of  the  Slide  Rule.     (Science  Series  No.  114.) i6mo,  o  50 

Worm  and  Spiral  Gearing.     (Science  Series  No.  116.) i6mo,  o  50 

Hancock,  H.     Textbook  of  Mechanics  and  Hydrostatics Svo,  i  50 

Hancock,  W.  C.  Refractory  Materials.  (Metallurgy  Series.)   (In  Press.) 

Hardy,  E.     Elementary  Principles  of  Graphic  Statics , i2mo,  *i  50 

Haring,  H.     Engineering  Law. 

Vol.  I.     Law  of  Contract Svo,  *4  oo 

Harper,  J.  H.     Hydraulic  Tables  on  the  Flow  of  Water i6mo,  *2  oo 

Harris,  S.  M.    Practical  Topographical  Surveying (In  Press.} 

Harrison,  W.  B.     The  Mechanics'  Tool-book I2mo,  i  50 

Hart,  J.  W.    External  Plumbing  Work Svo,  *3  25 

—  Hints   to   Plumbers   on  Joint   Wiping Svo,  *4  25 

Principles  of  Hot  Water  Supply Svo,  *4  25 

—  Sanitary    Plumbing   and   Drainage Svo,  *4  25 

Haskins,  C.  H.     The  Galvanometer  and  Its  Uses i6mo,  i  50 

Hatt,  J.  A.  H.     The  Colorist square  i2mo,  *i  50 

Hausbrand,  E.     Drying  by  Means  of  Air  and  Steam.     Trans,  by  A.  C. 

Wright i2mo,  *3  oo 

Evaporating,  Condensing  and  Cooling  Apparatus.     Trans,  by  A.  C. 

Wright Svo,  *7  25 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  13 

Hausmann,   E.     Telegraph   Engineering 8vo,  *3  oo 

Hausner,  A.     Manufacture  of  Preserved  Foods  and  Sweetmeats.     Trans. 

by  A.  Morris  and  H.  Robson 8vO,  *4  »J 

Hawkesworth,  J.     Graphical  Handbook  for  Reinforced  Concrete  Design. 

4to,  *2  50 

Hay,  A.    Continuous  Current  Engineering 8vo,  *2  50 

Hayes,  H.  V.    Public  Utilities,  Their  Cost  New  and  Depreciation. .  .8vo,  *2  oo 

—  Public  Utilities,  Their  Fair  Present  Value  and  Return 8vo,  *2  oo 

Heath,  F.  H.    Chemistry  of  Photography 8vo.  (In  Press.) 

Heather,  H.  J.  S.     Electrical  Engineering 8vo,  *3  50 

Heaviside,  O.     Electromagnetic  Theory.      Vols.  I  and  II.  ..  .8vo,  each,  *6  oo 

Vol.  Ill 8vo,  *io  oo 

Heck,  R.  C.  H.     The  Steam  Engine  and  Turbine 8vo,  *s  50 

Steam-Engine  and  Other  Steam  Motors.    Two  Volumes. 

Vol.    I.     Thermodynamics  and  the  Mechanics 8vo,  *3  50 

Vol.  II.     Form,  Construction,  and  Working 8vo,  *5  oo 

—  Notes  on  Elementary  Kinematics. . , 8vo,  boards,  *i  oo 

Graphics  of  Machine  Forces 8vo,  boards,  *i  oo 

Heermann,  P.    Dyers'  Materials.    Trans,  by  A.  C.  Wright i2mo,  *a  oo 

Heidenreich,    E.    L.     Engineers'    Pocketbook    of    Reinforced    Concrete, 

i6mo,  leather,  *3  oo 

Hellot,  Macquer  and  D'Apligny.   Art  of  Dyeing  Wool,  Silk  and  Cotton.  8vo,  *2  oo 

Henrici,  0.     Skeleton  Structures 8vo,  i  50 

Bering,  C.,  and  Getman,  F.  H.     Standard  Tables  of  Electro-Chemical 

Equivalents    izmo,  *2  oo 

Bering,  D.  W.    Essentials  of  Physics  for  College  Students 8vo,  *i  75 

Hering-Shaw,  A.     Domestic  Sanitation  and  Plumbing.     Two  Vols. .  .  8vo,  *5  oo 

Hering-Shaw,  A.     Elementary  Science 8vo,  *2  oo 

Herington,  C.  F.     Powdered  Coal  as  Fuel 8vo,  300 

Herrmann,  G.     The  Graphical  Statics  of  Mechanism.     Trans,  by  A.  P. 

Smith i2mo,  2  oc 

Herzfeld,  J.     Testing  of  Yarns  and  Textile  Fabrics 8vo,  *6  25 

Hildebrandt,  A.     Airships,  Past  and  Present 8vo, 

Hildenbrand,  B.  W.    Cable-Making.     (Science  Series  No.  32.)...  .i6mo,  o  50 

Hilditch,  T.  P.     A  Concise  History  of  Chemistry i2mo,  *i  50 

Hill,  C.  S.     Concrete  Inspection i6mo,  *i  oo 

Hill,  J.  W.    The  Purification  of  Public  Water  Supplies.    New  Edition. 

(In   Press.) 

—  Interpretation  of  Water  Analysis (In  Press.) 

Hill,  M.  J.  M.    The  Theory  of  Proportion 8vo,  *2  50 

Hillhouse,  P.  A.     Ship  Stability  and  Trim 8vo,  4  50 

HiroL  I.    Plate  Girder  Construction.     (Science  Series  No.  95.) .  .  .i6mo,  o  50 

Statically-Indeterminate  Stresses i2mo,  *2  oo 

Hirshfeld,  C.  F.    Engineering  Thermodynamics.  (Science  Series  No.  45.) 

i6mo,  o  50 

Hoar,  A.     The  Submarine  Torpedo  Boat i2mo,  *z  oo 

Habart,  H.  M.    Heavy  Electrical  Engineering 8vo,  *4  50 

Design  of  Static  Transformers i2mo,  *2  oo 

Electricity 8vo,  *2  oo 

Electric  Trains 8vo,  *2  50 

Electric  Propulsion  of  Ships 8vo,  *2  50 


14       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Eobart,  J.  F.    Hard  Soldering,  Soft  Soldering  and  Brazing ramo,  *r  oo 

Hobbs,  W.  R.  P.    The  Arithmetic  of  Electrical  Measurements. ..  .i2m»,  a  75 

iHoff,  J,  N.    Paint  and  Varnish  Facts  and  Formulas i2mor  *r  50 

Hole,  W.     The  Distribution  of  Gas 8vo,  *8  50 

Holley,  A.  L.     Railway  Practice folio,  6  oo 

Hopkins,  N.  M.    Model  Engines  and  Small  Boats i2mo,  r  25 

Hopkinson,  J.,  Shoolbred,  J.  N.,  and  Day,  R.  E.    Dynamic  Electricity. 

(Science  Series  No.  71.) i6mo,  o  50 

Horner,  J.     Practical  Ironfounding 8vo,  *2  oo 

Gear  Cutting,  in  Theory  and  Practice 8vo,  *s  oo 

Horniman,  Roy.    How  to  Make  the  Railways  Pay  For  the  War. . .  .8vo,  3  oo 

Houghton,  C.  E.    The  Elements  of  Mechanics  of  Materials i2mo,  *2  oo 

Houstoun,  R.  A.    Studies  in  Light  Production i2mo,  2  oo 

Hovenden,  F.     Practical  Mathematics  for  Young  Engineers i2mo,  *i  50 

Howe,  G.     Mathematics  for  the  Practical  Man.- i2mo,  *i  25 

Howorth,  J.     Repairing  and  Riveting  Glass,  China  and  Earthenware. 

8vo,  paper,  *i  oo 

Hoyt,  W.  E.     Chemistry  by  Experimentation 8vo,  *o  70 

Hubbard,  E.     The  Utilization  of  Wood-waste 8vo,  *s  oo 

Hiibner,  J.   Bleaching  and  Dyeing  of  Vegetable  and  Fibrous  Materials. 

(Outlines  of  Industrial  Chemistry.) 8vo,  *$  oo 

Hudson,  0.  F.    Iron  and  Steel.    (Outlines  of  Industrial  Chemistry. ).8vo,  *2  oo 
Humphrey,  J.  C.  W.     Metallography  of  Strain.     (Metallurgy  Series.) 

(In  Press.) 

Humphreys,  A.  C.    The  Business  Features  of  Engineering  Practice .  .8vo.  *i  25 

Hunter,  A.    Bridge  Work 8vo.  (In  Press.} 

Hurst,  G.  H.     Handbook  of  the  Theory  of  Color 8vo,  *4  25 

Dictionary  of  Chemicals  and  Raw  Products 8vo,  *6  25 

— —  Lubricating  Oils,  Fats  and  Greases 8vo,  *7  25 

—  Soaps 8vo,  *7  25 

Hurst,  G.  H.,  and  Simmons,  W.  H.     Textile  Soaps  and  Oils 8vo,  4  25 

Hurst,  H.  E.,  and  Lattey,  R.  T.     Text-book  of  Physics 8vo,  *s  oo 

—  Also   published  in  three  parts. 

Part      I.    Dynamics  and  Heat , *i  25 

Part    II.    Sound  and  Light *i  25 

Part  III.    Magnetism  and  Electricity *i  50 

Hutchinson,  R.  W.,  Jr.    Long  Distance  Electric  Power  Transmission. 

i2mo,  *3  oo 

Hutchinson,  R.  W.,  Jr.,  and  Thomas,  W.  A.    Electricity  in  Mining.  i2mo, 

(In  Press.) 
Hutchinson,  W.  B.     Patents  and  How  to  Make  Money  Out  of  Them. 

i2mo,  i  oo 

Hutton,  W.  S.    The  Works'  Manager's  Handbook 8vo,  6  oo 

Hyde,  E.  W.     Skew  Arches.     (Science  Series  No.  15.) i6mo,  o  50 

Eyde,  F.  S.     Solvents,  Oils,  Gums,  Waxes 8vo,  *2  oo 

Induction  Coils.     (Science  Series  No.  53.) i6mo,  o  50 

Ingham,  A.  E.    Gearing.    A  practical  treatise 8vo,  *2  50 

Ingle,  H.     Manual  of  Agricultural  Chemistry ,.8vo,  *4  25 


D    VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  15 

Inness,  C.  H.    Problems  in  Machine  Design i2mo,  *3  oo 

—  Air  Compressors  and  Blowing  Engines izmo, 

—  Centrifugal  Pumps  i2mo,  *s  oo 

-  The  Fan   i2mo,  *4  oo 

Jacob,  A.,  and  Gould,  E.  S.  On  the  Designing  and  Construction  of 

Storage  Reservoirs.  (Science  Series  No.  6) i6mo,  o  50 

Jannettaz,  E.  Guide  to  the  Determination  of  Rocks.  Trans,  by  G.  W. 

Plympton i2mo,  i  50 

Jehl,  F.     Manufacture  of  Carbons 8vo,  *4  oo 

Jennings,  A.  S.  Commercial  Paints  and  Painting.  (Westminster  Series.) 

8vo,  *4  oo 

Jenm'son,  F.  H.     The  Manufacture  of  Lake  Pigments 8vo,  *3  co 

Jepson,  G.     Cams  and  the  Principles  of  their  Construction 8vo,  *i  50 

—  Mechanical  Drawing 8vo  (In  Preparation.) 

Jervis-Smith,   F.  J.     Dynamometers 8vo,  *3  50 

Jockin,  W.     Arithmetic  of  the  Gold  and  Silversmith i2mo,  *i  oo 

Johnson,  J.  H.    Arc  Lamps  and  Accessory  Apparatus.     (Installation 

Manuals  Series.) i2mo,  *o  75 

Johnson,  T.  M.     Ship  Wiring  and  Fitting.     (Installation  Manuals  Series.) 

i2mo,  *o  75 

Johnson,  W.  McA.     The  Metallurgy  of  Nickel (In  Preparation.) 

Johnston,  J.  F.  W.,  and  Cameron,  C.     Elements  of  Agricultural  Chemistry 

and  Geology i2mo,  2  60 

Joly,  J.     Radioactivity  and  Geology i2mo,  ^3  oo 

Jones,  H.  C.     Electrical  Nature  of  Matter  and  Radioactivity i2mo,  *2  oo 

Nature  of  Solution 8vo,  *3  50 

New  Era  in  Chemistry i2mo,  *2  oo 

Jones,  J.  H.     Tinplate  Industry 8vo,  *3  oo 

Jones,  M.  W.     Testing  Raw  Materials  Used  in  Paint i2mo,  *3  oo 

Jordan,  L.  C.     Practical  Railway  Spiral i2mo,  leather,  *i  50 

Joynson,  F.  H.     Designing  and  Construction  of  Machine  Gearing  .  .8vo,  2  oo 

Jiiptner,  H.  F.  V.     Siderology:  The  Science  of  Iron 8vo,  *6  25 

Kapp,  G.    Alternate  Current  Machinery.     (Science  Series  No.  96.). i6mo,  o  50 

Kapper,  F.     Overhead  Transmission  Lines 4to,  "4  oo 

Keim,  A.  W.    Prevention  of  Dampness  in  Buildings 8vo,  *3  oo 

Keller,  S.  S.     Mathematics  for  Engineering  Students.     1 2mo,  half  leather. 

—  and  Knox,  W.  E.    Analytical  Geometry  and  Calculus *2  oo 

Kelsey,  W.  R.     Continuous-current  Dynamos  and  Motors 8vo,  *2  50 

Kemble,  W.  T.,  and  Underbill,  C.  R.     The  Periodic  Law  and  the  Hydrogen 

Spectrum 8vo,  paper,  *o  50 

Kemp,  J.  F.     Handbook  of  Rocks 8vo,  *i  50 

Kennedy,  A.  B.  W.,  and  Thurston,  R.  H.    Kinematics  of  Machinery. 

(Science  Series  No.  ?d.) i6rro,  o  50 

Kennedy,  A.  B.  W.,  Unwin,  W.  C.,  and  Well,  F.  E.     Compressed   Air! 

(Science  Series  No.  106.) ^mo,  o  50 


If       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Kennedy,  R.     Electrical  Installations.    Five  Volumes 4to,  15  oo 

Single  Volumes each,  3  50 

Flying  Machines ;  Practice  and  Design i2ino,  *2  50 

Principles  of  Aeroplane  Construction 8vo,  *a  oo 

Kennelly,  A.  E.     Electro-dynamic  Machinery 8vo,  i  50 

Kent,  W.     Strength  of  Materials.     (Science  Series  No.  41.) i6mo,  o  50 

Kershaw,  J.  B.  C.     Fuel,  Water  and  Gas  Analysis 8vo,  *2  50 

Electrometallurgy.     (Westminster  Series.) 8vo,  *2  oo 

The  Electric  Furnace  in  Iron  and  Steel  Production i2mo, 

Electro-Thermal   Methods   of  Iron   and   Steel   Production.  ..  .8vo,  *s  oo 

Kindelan,  J.     Trackman's  Helper tamo,  2  oo 

Kinzbrunner,  C.     Alternate  Current  Windings 8vo,  *i  50 

Continuous  Current  Armatures 8vo,  *i  50 

Testing  of  Alternating  Current  Machines 8vo,  *2  oo 

Kirkaldy,    A..    W.,    and    Evans,    A.    D.      History    and    Economics    of 

Transport 8vo,  *3  oo 

Kirkaldy,  W.  G.    David  Kirkaldy' s  System  of  Mechanical  Testing ..  4to,  10  oo 

Kirkbride,  J.     Engraving  for  Illustration 8vo,  *i  75 

Kirkham,  J.  E.     Structural  Engineering 8vo,  *5  oo 

Kirkwood,  J.  P.    Filtration  of  River  Waters 4to,  7  50 

Kirschke,  A.     Gas  and  Oil  Engines i2mo,  *i  50 

Klein,  J.  F.    Design  of  a  High-speed  Steam-engine 8vo,  *5  oo 

—  Physical  Significance  of  Entropy 8vo,  *i  50 

Klingenberg,  G.     Large   Electric   Power  Stations 4to,  *5  oo 

Knight,  R.-Adm.  A.  M.     Modern  Seamanship 8vo,  *6  50 

—  Pocket   Edition i2mo,   f abrikoid,  3  oo 

Knott,  C.  G.,  and  Mackay,  J.  S.     Practical  Mathematics 8vo,  2  50 

Knox,  G.  D.    Spirit  of  the  Soil i2mo,  *i  25 

Knox,  J.     Physico-Chemical  Calculations i2mo,  *i  25 

Fixation  of  Atmospheric  Nitrogen.      (Chemical  Monographs.)  .i2mo,  *i  oo 

Koester,  F.     Steam-Electric  Power  Plants 4to,  *5  oo 

— —  Hydroelectric  Developments  and  Engineering 4to,  *5  oo 

Koller,  T.     The  Utilization  of  Waste  Products 8vo,  *6  50 

—  Cosmetics 8vo,  *s  oo 

Koppe,  S.  W.    Glycerine i2mo,  *4  25 

Kozmin,  P.  A.     Flour  Milling.     Trans,  by  M.  Falkner 8vo,  7  50 

Kremann,  R.     Application  of  the  Physico-Chemical  Theory  to  Tech- 
nical  Processes   and  Manufacturing   Methods.     Trans,  by  H. 

E.  Potts 8vo,  *s  oo 

Kretchmar,  K.     Yarn  and  Warp  Sizing ,,,,,, ,tt ,, t, ,8vo,  *6  25 

Laff argue,  A.    Attack  in  Trench  Warfare «••••••••*.  I6mo,  o  50 

Lallier,  E.  V.    Elementary  Manual  of  the  Steam  Engine i2mo,  *2  oo 

Lambert,  T.     Lead  and  Its   Compounds 8vo,  *4  25 

Bone  Products  and  Manures  8vo,  *4  25 

Lamborn,  L.  L.     Cottonseed  Products 8vo,  *3  oo 

—  Modern  Soaps,  Candles,  and  Glycerin 8vo,  *7  50 

Lamprecht,  R.  Recovery  Work  After  Pit  Fires.  Trans,  by  C.  Salter.Svo,  *6  25 

Lancaster,  M.     Electric  Cooking,  Heating  and  Cleaning 8vo,  *i  oo 

Lanchester,  F.  W.    Aerial  Flight    Two  Volumes.    8vo. 

Vol.  I.     Aerodynamics .  *6  oo 

Vol.   II.     Aero* 'vi  Mies..  *6  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  17 

Lanchester,  F.  W.    The  Flying  Machine 8vo,  *s  oo 

—  Industrial   Engineering:    Present   and   Post-War   Outlook.  .  .lamo,  i  oo 

Lange,  K.  R.    By-Products  of  Coal-Gas  Manufacture i2mo,  3  oo 

Lamer,  E.  T.     Principles  of  Alternating  Currents i2mo.  *i  2* 

La  Rue,  B.  F.     Swing  Bridges.     (Science  Series  No.  107.) i6mo,  05, 

Lassar-Cohn.  Dr.     Modern  Scientific   Chemistry.     Trans,  by  M.   M. 

Pattison  Muir i2mo,  *2  oo 

Latimer,  L.  H.,  Field,  C.  J.,  and  Howell,  J.  W.  Incandescent  Electric 

Lighting.  (Science  Series  No.  57.)  : i6mo,  o  50 

Latta,  M.  N.  Handbook  of  American  Gas-Engineering  Practice  .  .  .8vo,  *4  50 

American  Producer  Gas  Practice 4to,  *6  oo 

Laws,  B.  C.  Stability  and  Equilibrium  of  Floating  Bodies 8vo,  *s  50 

Lawson,  W.  R.  British  Railways.  A  Financial  and  Commercial 

Survey 8vo,  200 

Leask,  A.  R.  Breakdowns  at  Sea i2mo,  2  oo 

Refrigerating  Machinery i2mo,  2  oo 

Lecky,  S.  T.  S.  "Wrinkles"  in  Practical  Navigation 8vo,  10  oo 

—  Pocket    Edition    i2mo,  4  50 

Danger    Angle    i6mo,  2  50 

Le  Doux,  M.     Ice-Making  Machines.     (Science  Series  No.  46.) . .  i6mo,  o  50 

Leeds,  C.  C.    Mechanical  Drawing  for  Trade  Schools oblong  4to,  *2  oo 

Mechanical  Drawing  for  High  and  Vocational  Schools 4to,  *i  25 

Lefevre,  L.     Architectural  Pottery.     Trans,  by  H.  K.  Bird  and  W.  M. 

Binns 4to,  *8  50 

Lehner,  S.    Ink  Manufacture.    Trans,  by  A.  Morris  and  H.  Robson.Svo,  *3  oo 

Lemstrom,  S.     Electricity  in  Agriculture  and  Horticulture.. 8vo,  *i  50 

Letts,  E.  A.     Fundamental  Problems  in  Chemistry 8vo,  *2  oo 

Le  Van,  W.  B.    Steam-Engine  Indicator.    (Science  Series  No.  78.)i6mo,  o  50 

Lewes,  V.  B.    Liquid  and  Gaseous  Fuels.     (Westminster  Series.) .  .8vo,  *2  oo 

—  Carbonization   of   Coal 8vo,  *5  oo 

Lewis,  L.  P.     Railway  Signal  Engineering 8vo,  *3  50 

Lewis  Automatic  Machine  Rifle  ;  Operation  of i6mo,    *o  75 

Licks,  H.  E.     Recreations  in  Mathematics i2mo,  *i  25 

Lieber,  B.  F.     Lieber's  Five  Letter  American  Telegraphic  Code  .8vo,  *is  oo 

——* Spanish   Edition    8vo,  *is  oo 

—  French   Edition    8vo,  *is  oo 

—  Terminal  Index 8vo,  *2  50 

Lieber's  Appendix folio,  *is  oo 

—  Handy  Tables 4*0,  *2  50 

—  Bankers  and  Stockbrokers'  Code  and  Merchants  and  Shippers' 

Blank  Tables 8vo,  *is  oo 

ioo}ooo,ooo  Combination  Code 8vo,  *io  oo 

Engineering  Code 8vo,  *i2  50 

Livermore,  V.  P.,  and  Williams,  J.    How  to  Become  a  Competent  Motor- 
man I2H1O,  *I    00 

Livingstone,  R.     Design  and  Construction  of  Commutators 8vo,  *2  25 

—  Mechanical  Design  and  Construction  of  Generators 8vo,  *3  50 

Lloyd,  S.  L.     Fertilizer  Materials i2mo,  a  oo 

Lobben,  P.     Machinists'  and  Draftsmen's  Handbook 8vo,  2  50 

Lockwood,  T.  D.     Electi icily ;  Magnetism,  and  Electro-telegraph   ..    .8vo,    250 
Electrical  Measurement  and  the  Galvanometer i2mo,  o  75 


!8       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Lodge,  O.  J.  Elementary  Mechanics i2mo,  i  50 

Signalling  Across  Space  without  Wires 8vo,  *2  oo 

Loewenstein,  L.  C.}  and  Crissey,  C.  P.     Centrifugal  Pumps *4  50 

Lomax,  J.  W.     Cotton  Spinning i2mo,  i  50 

Lord,  R.  T.     Decorative  and  Fancy  Fabrics 8vo,  *4  25 

Loring,  A.  E.    A  Handbook  of  "the  Electromagnetic  Telegraph ....  i6mo  o  50 

Handbook.     (Science  Series  No.  39.) i6m,  o  50° 

Lovell,  D.  H.     Practical  Switchwork i2mo,  *i  oo 

Low,  D.  A.    Applied  Mechanics  (Elementary) i6mo,  o  80 

Lubschez,  B.  J.    Perspective i2mo,  *i  50 

Lucke,  C.  E.     Gas  Engine  Design 8vo,  *3  oo 

Power  Plants:  Design,  Efficiency,  and  Power  Costs.    2  vols. 

(In  Preparation.) 

Luckiesh,  M.     Color  and  Its  Application 8vo,  *3  oo 

—  Light  and  Shade  and  Their  Applications 8vo,  *2  50 

Lunge,  G.    Coal-tar  and  Ammonia.     Three  Volumes 8vo,  *25  oo 

—  Technical  Gas  Analysis 8vo,  *4  50 

Manufacture  of  Sulphuric  Acid  and  Alkali.    Four  Volumes ....  8vo, 

Vol.     I.     Sulphuric  Acid.    In  three  parts *i8  oo 

Vol.  I.    Supplement 8vo,  5  oo 

Vol.  II.     Salt  Cake,  Hydrochloric  Acid  and  Leblanc  Soda.    In  two 

parts    (In  Press.) 

Vol.  III.    Ammonia  Soda (In  Press.) 

Vol.  IV.     Electrolytic  Methods (In  Press.) 

Technical  Chemists'  Handbook i2mo,  leather,  *4  oo 

Technical  Methods  of  Chemical  Analysis.    Trans,  by  C.  A.  Keane 

in  collaboration  with  the  corps  of  specialists. 

Vol.     I.     In  two  parts 8vo,  *i5  oo 

Vol.   II.     In  two  parts 8vo,  *i8  oo 

Vol.   III.     In  two  parts 8vo,  *i8  oo 

The  set    (3  vols.)    complete. *5o  oo 

Luquer,  L.  M.     Minerals  in  Rock  Sections 8vo,  *i  50 

MacBride,  J.  D.     A  Handbook  of  Practical  Shipbuilding, 

i2mo,  fabrikoid,  2  oo 

Macewen,  K.  A.     Food  Inspection 8vo,  *2  50 

Mackenzie,  N.  F.     Notes  on  Irrigation  Works 8vo,  *2  50 

Mackie,  J.    How  to  Make  a  Woolen  Mill  Pay 8vo,  *2  25 

Maguire,  V/m.  R.    Domestic  Sanitary  Drainage  and  Plumbing  ....  8vo,  4  oo 

Malcolm,  C.  W.    Textbook  on  Graphic  Statics .8vo,  *3  oc 

Malcolm,  E.  W.     Submarine  Telegraph  Cable 8  50 

Mallet,  A.     Compound  Engines.     Trans,  by  R.  R.  Buel.     (Science  Series 

No.  10.) i6mo, 

Mansfield,  A.  N.     Electro-magnets.     (Science  Series  No.  64.)  . .    i6mo,  o  50 

Marks,  E.  C.  R.    Construction  of  Crane*  STIC!  Lifting  Machinery,  .  r^mo,  *2  oo 

Construction  and  Working  of  Pumps i?mo, 

— —  Manufacture  of  Iron  and  Steel  Tubes ismo,  *2  oo 

Mechanical  Engineering  Materials i-zmo,  *i  50 

Marks,  G.  C.     Hydraulic  Power  Engineering 8vo,  4  *o 

—  Inventions,  Patents  and  Designs 12^0,  *T  oo 

Marlow,  T.  G.     Drying  Machinery  and  Practice 8vo,  *s  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  19 

Marsh,  C.  F.     Concise  Treatise  on  Reinforced  Concrete  8vo,  *2  50 

• Reinforced  Concrete  Compression  Member  Diagram.     Mounted  on 

Cloth  Boards *i  .50 

Marsh,  C.  F.,  and  Dunn,  W.     Manual  of  Reinforced  Concrete  and  Con- 
crete Block  Construction i6mo,  fabrikoid  (In  Press.} 

Marshall,  W.  J.,  and  Sankey,  H.  R.     Gas  Engines.     (Westminster  Series.) 

8vo,  *2  oo 

Martin,  G.     Triumphs  and  Wonders  of  Modern  Chemistry 8vo,  *2  oo 

—  Modern   Chemistry  and  Its  Wonders 8vo,  *2  oo 

Martin,  N.     Properties  and  Design  of  Reinforced  Concrete i2mo,  *2  50 

Martin,  W.  D.    Hints  to  Engineers 12010,  *i  50 

Massie,  W.  W.,  and  Underbill,  C.  R.     Wireless  Telegraphy  and  Telephony. 

i2mo,  *i  oo 

Mathot,  R.  E.     Internal  Combustion  Engines 8vo,  *4  oo 

Maurice,  W.     Electric  Blasting  Apparatus  and  Explosives 8vo,  *3  50 

• Shot  Firer's  Guide 8vo,  *i  50 

Maxwell,  F.     Sulphitation  in  White  Sugar  Manufacture i2mo,  3  75 

Maxwell,     J.     C.       Matter    and  Motion.       (Science   Series  No.  36.). 

i6mc,  o  50 

Maxwell,  W.  H.,  and  Brown,  J.  T.     Encyclopedia  of  Municipal  and  Sani- 
tary Engineering 4to,  *io  oo 

Mayer,  A.  M.     Lecture  Notes  on  Physics 8vo,  2  oo 

Mayer,  C.,  and  Slippy,  J.  C.    Telephone  Line  Construction 8vo,  *3  oo 

McCullough,  E.    Practical  Surveying lamo,  *2  oo 

—  Engineering  Work  in  Cities  and  Towns 8vo,  *3  oo 

—  Reinforced  Concrete    lamo,  *i  50 

McCullough,  R.  S.     Mechanical  Theory  of  Heat 8vo,  3  50 

McGibbon.  W.  C.    Indicator  Diagrams  for  Marine  Engineers 8vo,  "3  50 

—  Marine  Engineers'  Drawing  Book .oblong  4to,  *2  50 

McGibbon,  W.  C.    Marine  Engineers  Pocketbook i2mo,  *4  50 

Mclntosh,  J.  G.     Technology  of  Sugar 8vo,  *7  25 

—  Industrial  Alcohol    8vo,  *4  25 

Manufacture  of  Varnishes  and  Kindred  Industries.     Three  Volumes. 

8vo. 

Vol.     I.     Oil  Crushing,  Refining  and  Boiling 

Vol.  II.     Varnish  Materials  and  Oil  Varnish  Making. *6  25 

Vol.  III.     Spirit  Varnishes   and   Materials **/  25 

McKay,   C.   W.     Fundamental   Principles   of   the  Telephone   Business. 

8vo.    (In  Press.) 

McKillop,  M.,  and  McKillop,  A.  D.     Efficiency  Methods i2mo,  i  50 

McKnifht,  J.  D.,  and  Brown,  A.  W.     Marine  Multitubular  Boilers *2  50 

McMaster,  J.  B.     Bridge  and  Tunnel  Centres.     (Science  Series  No.  20.) 

i6mo,  o  50 

McMechen,  F.  L.     Tests  for  Ores,  Minerals  and  Metals i2mo,  *i  oo 

McPherson,  J.  A.     Water-works  Distribution 8vo,  2  50 

Meade,   A.     Modern   Gas   Works   Practice fivo,  *3  50 

Meide,  R.  K.    Design  a^J  TLquipment  of  Small  Chemical  Laboratcr'e?, 

Svo, 

Melick,  C.  W.     Dairy  Laboratory  Guide i2mo,  *i  25 

Mensch,  L.  J.     Reinforced  Concrete  Pocket  Book i6mo,  leather,  *4  oo 

Merck,  E.     Chemical   Reagents;  Their  Purity  and  Tests.     Trans,   by 

H.   E.   Schenck Svo,  i  oo 

Meriva's,  J.  H.     Notes  and  Formulae  for  Mining  Students izmo,  i  50 

Merritt,  Wm.  H.    Field  Testing  for  Gold  and  Silver i6mo,  leather,  2  oo 


20       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Mertens.     Tactics  and  Technique  of  River  Crossings.     Translated  by 

W.    Kruger 8vo,  250 

Mierzinski,  S.     Waterproofing  of  Fabrics.     Trans,  by  A.  Morris  and  H. 

Robson 8vo,  *3  oo 

Miessner,  B.  F.    Radio  Dynamics i2mo,  *a  oo 

Miller,  G.  A.     Determinants.     (Science  Series  No   105.) i6mo, 

Miller,  W.  J.     Introduction  to  Historical  Geology i2mo,  *2  oo 

Milroy,  M.  E.  W.     Home  Lace-making 12010,  *i  oo 

Mills,  C.  N.    Elementary  Mechanics  for  Engineers 8vo,  *i  oo 

Mitchell,  C.  A.     Mineral  and  Aerated  Waters 8vo,  *3  oo 

Mitchell,  C.  A.,  and  Prideaux,  R.  M.     Fibres  Used  in  Textile  and  Allied 

Industries 8vo,  *3  oo 

Mitchell,  C.  F.,  and  G.  A.     Building  Construction  and  Drawing.     12010. 

Elementary  Course *i  50 

Advanced  Course *2  50 

Monckton,  C.  C.  F.     Radiotelegraphy.     (Westminster  Series.) 8vo,  *2  oo 

Monteverde,  R.  D.     Vest  Pocket  Glossary  of  English-Spanish,  Spanish- 
English  Technical  Terms 64010,  leather,  *i  oo 

Montgomery,  J.  H.     Electric  Wiring  Specifications i6mo,  *i  oo 

Moore,  E.  C.  S.     New  Tables  for  the  Complete  Solution  of  Ganguillet  and 

Kutter's  Formula 8vo,  *s  oo 

Moore,  Harold.     Liquid  Fuel  for  Internal  Combustion  Engines .  . .  8vo,  5  oo 
Morecroft,  J.  H.,  and  Hehre,  F.  W.     Short  Course  in  Electrical  Testing. 

8vo,  *i  50 

Morgan,  A.  P.     Wireless  Telegraph  Apparatus  for  Amateurs 12010,  *i  50 

Morgan,  C.  E.     Practical  Seamanship  for  the  Merchant  Marine, 

xarno,  fabrikoid   (In  Press.) 

Moses,  A.  J.     The  Characters  of  Crystals 8vo,  *2  oo 

—  and  Parsons,  C.  L.     Elements  of  Mineralogy 8vo,  *s  50 

Moss,  S.A.  Elements  of  Gas  Engine  Design. (Science  Series  No.  121. )i6mo,  o  50 

-  The  Lay-out  of  Corliss  Valve  Gears.     (Science  Series  No.  1 19.)  16010,  o  50 

Mulford,  A.  C.     Boundaries  and  Landmarks 12010,  *i  oo 

Mullin,  J.  P.     Modern  Moulding  and  Pattern-making 12010,  2  50 

Munby,  A.  E.     Chemistry  and  Physics  of  Building  Materials.     (West- 
minster Series.) 8vo,  *2  oo 

Murphy,  J.  G.     Practical  Mining i6mo,  i  oo 

Murray,  J.  A.     Soils  and  Manures.     (Westminster  Series.) 8vo,  *2  oo 

Nasmith,  J.     The  Student's  Cotton  Spinning. 8vo,  4  50 

—  Recent  Cotton  Mill  Construction 12010,  2  50 

Neave,  G.  B.,  and  Heilbron,  I.  M.     Identification  of  Organic  Compounds. 

12010,  *i  25 

Neilson,  R.  M.    Aeroplane  Patents 8vo,  *2  oo 

Nerz,  F.     Searchlights.     Trans,  by  C.  Rodgers 8vo,  *3  oo 

Neuberger,  H.,  and  Noalhat,  H.     Technology  of  Petroleum.     Trans,  by 

J.  G.  Mclntosh 8vo,  *io  oo 

Newall,  J.  W.    Drawing,  Sizing  and  Cutting  Bevel-gears 8vo,  i  50 

Newbigin,  M.  I.,  and  Flett,  J.  S.     James  Geikie,  the  Man  and  the 

Geologist 8vo,  3  50 

Newbeging,  T.     Handbook  for  Gas  Engineers  and  Managers 8vo,  *6  50 

Newell,  F.  H.,  and  Drayer,  C.  E.    Engineering  as  a  Career.  .12010,  cloth,  ;:  i  oo 

paper,  o  75 

Nicol,  G.     Ship  Construction  and  Calculations 8vo,  *io  oo 

Nipher,  F.  E.    Theory  of  Magnetic  Measurements 12010,  i  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  21 

Jfisbet,  H.     Grammar  of  Textile  Design 8vo, 

Nolan,  H.     The  Telescope.     (Science  Series  No.  51.) i6mo,  o  50 

Norie,  J.  W.    Epitome  of  Navigation  (2  Vols.) octavo,  15  oo 

—  A  Complete  Set  of  Nautical  Tables  with  Explanations  of  Their 

Use    octavo,  6  50 

North,  H.  B.    Laboratory  Experiments  in  General  Chemistry i2mo,  *i  oo 

Nugent,  E.     Treatise  on  Optics .  i2mo,  i  50 

O'Connor,  H.  The  Gas  Engineer's  Pocketbook i2mo,  leather,  3  50 

Oiim,  G.  S.,  and  Lockwood,  T.  D.  Galvanic  Circvit  Translated  by 

William  Francis.  (Science  Series  No.  102  , i6mo,  o  50 

Olsen,  J.  C.  Text-book  of  Quantitative  Chemical  Analysis 8vo,  3  50 

Olsson,  A.  Motor  Control,  in  Turret  Turning  and  Gun  Elevating.  (U.  S. 

Navy  Electrical  Series,  No.  i.) i2mo,  paper,  *o  50 

Ormsby,  M.  T.  M.  Surveying i2mo  2  50 

Oudin,  M.  A.  Standard  Polyphase  Apparatus  and  Systems 8vo,  *3  oo 

Owen,  D.  Recent  Physical  Research 8vo, 

Pakes,  W.  C.  C.,  and  Nankivell,  A.  T.     The  Science  of  Hygiene  .  .8vo,  *i  75 

Palaz,  A.     Industrial  Photometry.     Trans,  by  G.  W.  Patterson,  Jr .  .  8vo,  *4  oo 

Palmer,  A.   R.     Electrical   Experiments i2mo,  075 

—  Magnetic  Measurements  and  Experiments i2mo,  o  75 

Pamely,  C.     Colliery  Manager's  Handbook 8vo,  *io  oo 

Parker,  P.  A.  M.     The  Control  of  Water 8vo,  *5  oo 

Parr,  G.  D.  A.     Electrical  Engineering  Measuring  Instruments.  ..  .8vo,  *3  50 
Parry,  E.  J.    Chemistry  of  Essential  Oils  and  Artificial  Perfumes....  10  oo 
Foods  and  Drugs.     Two  Volumes. 

Vol.  I.    Chemical  and  Microscopical  Analysis  of  Foods  and  Drugs.  *io  oo 

Vol.  II.     Sale  of  Food  and  Drugs  Act *4  25 

" and  Coste,  J.  H.    Chemistry  of  Pigments 8vo,  *6  50 

Parry,  L.     Notes  on  Alloys 8vo,  *3  50 

Metalliferous  Wastes    8vo,  *2  50 

—  Analysis  of  Ashes  and  Alloys 8vo,  *2  50 

Parry,  L.  A.     Risk  and  Dangers  of  Various  Occupations 8vo,  *4  25 

Parshall,  H.  F.,  and  Hobart,  H.  M.     Armature  Windings    4to,  *7  50 

Electric  Railway  Engineering 4to,  *io  oo 

Parsons,  J.  L.     Land  Drainage 8vo,  *i  50 

Parsons,  S.  J     Malleable  Cast  Iron 8vo,  *2  50 

Partington,  J.  R.    Higher  Mathematics  for  Chemical  Students.  .i2mo,  *2  oo 
Textbook  of  Thermodynamics 8vo,  *4  oo 

—  The    Alkali    Industry 8vo,  3  oo 

Passmore,  A.  C.    Technical  Terms  Used  in  Architecture 8vo,  *4  25 

Patchell,  W.  H.     Electric  Power  in  Mines 8vo,  *4  oo 

Paterson,  G.  W.  L.     Wiring  Calculations i2mo,  *3  oo 

Electric  Mine  Signalling  Installations i2mo,  *i  50 

Patterson,  D.     The  Color  Printing  of  Carpet  Yarns 8vo,  *4  25 

— —  Color   Matching  on   Textiles 8vo,  *4  25 

Textile  Color  Mixing 8vo,  *4  25 

Paulding,  C.  P.     Condensation  of  Steam  in  Covered  and  Bare  Pipes .  .  8vo,  *2  oo 

Transmission  of  Heat  through  Cold-storage  Insulation i2mo,  *i  oo 

Payne,  D.  W.     Iron  Founders'  Handbook 8vo,  *4  oo 

Peckham,  S.  F.     Solid  Bitumens 8vo,  *5  oo 

Peddie,  R.  A.     Engineering  and  Metallurgical  Books i2mo,  *i  50 

Peirce,  B.     System  of  Analytic  Mechanics  4to,  10  oo 

— —  Linnear   Associative   Algebra 4to,  3  oo 

Pendred,  V.     The  Railway  Locomotive,     (Westminster  Series.) 8vo,  *2  oo 


22       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Perkin,  F.  M.    Practical  Methods  of  Inorganic  Chemistry i2mo,  *i  oo> 

Perrin,  J.     Atoms 8vo,  *2  50 

and  Jaggers,  E.  M.    Elementary  Chemistry i2mo,  *i  oo 

Perrine,  F.  A.  C.     Conductors  for  Electrical  Distribution 8vo,  *3  50 

Petit,  G.    White  Lead  and  Zinc  White  Paints 8vo,  *2  50 

Petit,  R.     How  to  Build  an  Aeroplane.     Trans,  by  T.  O'B.  Hubbard,  and 

J.  H.  Ledeboer 8vo,  *i  50 

Pettit,  Lieut.  J.  S.     Graphic  Processes.     (Science  Series  No.  76.) . . .  i6mo,  o  50 
Philbrick,  P.  H.     Beams  and  Girders.     (Science  Series  No.  88.) . .  .  i6mo, 

Phillips,  J.     Gold   Assaying 8vo,  *s  75 

Dangerous  Goods 8vo,  3  50 

Phin,  J.     Seven  Follies  of  Science i2mo,  *i  50 

Pickworth,  C.  N.     The  Indicator  Handbook.     Two  Volumes.  .12010,  each,  i  50 

Logarithms  for  Beginners i2mo,  boards,  o  50 

—  The  Slide  Rule i2mo,  i  50 

Pilcher,  R.  B.,  and  Butler-Jones,  F.    What  Industry  Owes  to  Chemical 

Science i2mo,  i  50 

Plattner's  Manual  of  Blow-pipe  Analysis.    Eighth  Edition,  revised.    Trans. 

by  H.  B.  Cornwall 8vo,  *4  oo 

Plympton,  G.  W.    The  Aneroid  Barometer.    (Science  Series  No.  35.)   i6mo,  o  50 

How  to  become  an  Engineer.     (Science  Series  No.  100.) i6mo,  o  50 

Van  Nostrand's  Table  Book.     (Science  Series  No.  104.) i6mo,  o  50 

Pochet,  M.  L.     Steam  Injectors.     Translated  from  the  French.     (Science 

Series  No.  29.) , .  i6mo,  o  50 

Pocket  Logarithms  to  Four  Places.     (Science  Series  No.  65.) i6mo,  o  50 

leather,  i  oo 

Polleyn,  F.     Dressings  and  Finishings  for  Textile  Fabrics 8vo,  *3  oo 

Pope,  F.  G.    Organic  Chemistry i2mo,  2  50 

Pope,  F.  L.     Modern  Practice  of  the  Electric  Telegraph 8vo,  i  50 

Popplewell,  W.  C.     Prevention  of  Smoke .8vo,  *4  25 

—  Strength  of  Materials 8vo,  *2  50 

Porritt,  B.   D.     The   Chemistry   of   Rubber.      (Chemical   Monographs, 

No.  3.) i2mo,  *i  oo 

Porter,  J.  R.    Helicopter  Flying  Machine . .   i2mo,  i  50 

Potts,  H.  E.     Chemistry  of  the  Rubber  Industry.     (Outlines  of  Indus- 
trial  Chemistry) 8vo,  *2  50 

Practical  Compounding  cf   Oils,  Tallow  and   Grease 8vo,  *4  25 

Pratt,  K.     Boiler  Draught I2mo,  *i  25 

High  Speed  Steam   Engines. 8vo,  *2  oo 

Pray,  T.,  Jr.     Twenty  Years  with  the  Indicator 8vo,  2  50 

—  Steam  Tables  and  Engine  Constant 8vo,  2  oo 

Prelini,  C.     Earth  and  Rock  Excavation 8vo,  *3  oo 

Graphical  Determination  of  Earth  Slopes 8vo,  *2  oo 

Tunneling.     New  Edition 8vo,  *3  oo 

Dredging.     A  Practical  Treatise 8vo,  *3  oo 

Prescott,  A.  B.     Organic  Analysis 8vo,  5  oo 

Prescott,  A.  B.,  and  Johnson,  O.  C,     Qualitative  Chemical  Analysis. .  .8vo,  *3  50 
Prescott,  A.  B.,  and  Sullivan,  E.  C.     First  Book  in  Qualitative  Chemistry. 

I2mo,  *i  50 

Prideaux,  E.  B.  R.     Problems  in  Physical  Chemistry 8vo,  *2  oo 

The  Theory  and  Use  of  Indicators.  . .    8vo,  5  oo 

Primrose,  G.  S.  C.     Zinc.     (Metallurgy  Series.) (In  Press.} 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  23 

Prince,  G.  T.     Flow  of  Water '. . . . i2mo,  *2  oo 

Pull,  E.     Modern  Steam  Boilers 8vo,  5  oo . 

Pullen,   W.  W.  F.     Application  of  Graphic  Methods  to  the  Design  of 

Structures i2mo,  *2  50 

Injectors:    Theory,   Construction   and  Working. 12 mo,  *2  oo 

Indicator  Diagrams    .' 8vo,  *2  50 

—  Engine  Testing  8vo,  *5  50 

putsch,  A.     Gas  and  Coal-dust  Firing 8vo,  *3  oo 

Pynchon,  T.  R.     Introduction  to  Chemical  Physics 8vo,  3  oo 

Rafter  G.  W      Mechanics  of  Ventilation.     (Science  Series  No.  33.) .  i6mo,  o  53 
Potable  Water.     (Science  Series  No.  103.) '.  .i6mo,  o  50 

—  Treatment  of  Septic  Sewage.     (Science  Series  No.  118.)  .  . .  i6mo,  o  50 
Rafter,  G.  W.,  and  Baker,  M.  N.     Sewage  Disposal  in  the  United  States. 

4to,  *6  oo 

Raikes,  H.  P.     Sewage  Disposal  Works 8vo,  *4  oo 

Randau,  P.  Enamels  and  Enamelling 8vo,  *7  25 

Rankine,  W.  J.  M.     Applied  Mechanics 8vo,  5  oo 

—  Civil  Engineering 8vo,  6  50 

-  Machinery  and  Millwork 8vo,  5  oo 

-  The  Steam-engine  and  Other  Prime  Movers 8vo,  5  oo 

Rankine,  W.  J.  M.,  and  Bamber,  E.  F.     A  Mechanical  Text-book 8vo,  3  50 

Ransome,  W.  R.    Freshman  Mathematics i2mo,  *i  35 

Raphael,  F.  C.     Localization  of  Faults  in  Electric  Light  and  Power  Mains. 

8vo,  3  50 

Rasch,  E.    Electric  Arc  Phenomena.    Trans,  by  K.  Tornberg 8vo,  *2  oo 

Rathbone,  R.  L.  B.     Simple  Jewellery 8vo,  *2  oo 

Rateau,  A.     Flow  of  Steam  through  Nozzles  and  Orifices.     Trans,  by  H. 

B.  Brydon 8vo  *i  50 

Rausenberger,  F.     The  Theory  of  the  Recoil  Guns. 8vo,  *5  oo 

Rautenstrauch,  W.     Notes  on  the  Elements  of  Machine  Design. 8vo,  boards,  *i  50 
Rautenstrauch,  W.,  and  Williams,  J.  T.     Machine  Drafting  and  Empirical 
Design. 

Part   I.  Machine  Drafting 8vo,  *i  25 

Part  II.  Empirical  Design (In  Preparation.) 

Raymond,  E.  B.     Alternating  Current  Engineering I2mo,  *2  50 

Rayner,  H.     Silk  Throwing  and  Waste  Silk  Spinning 8vo, 

Recipes  for  the  Color,  Paint,  Varnish,  Oil,  Soap  and  Drysaltery  Trades, 

8vo,  *6  50 

Recipes  for  Flint  Glass  Making i2mo,  *s  25 

Redfern,  J.  B.,  and  Savin,  J.    Bells,  Telephones  (Installation  Manuals 

Series.) i6mo,  *o  50 

Redgrove,  H.  S.     Experimental  Mensuration i2mo,  *i  25 

Redwood,  B.     Petroleum.     (Science  Series  No.  92.) i6mo,  o  50 

Reed,  S.    Turbines  Applied  to  Marine  Propulsion *5  oo 

Reed's  Engineers'  Handbook.  ...    gvo,  *g  oo 

Key  to  the  Nineteenth  Edition  of  Reed's  Engineers'  Handbook.  .8vo,  4  oo 

Useful  Hints  to  Sea-going  Engineers i2mo,  3  oo 

Reid,  E.  E.    Introduction  to  Research  in  Organic  Chemistry.  (In  Press.) 

Reid,  H.  A.     Concrete  and  Reinforced  Concrete  Construction 8vo,  *$  oo 

Reinhardt,  C  W.     Lettering  for  Draftsmen,  Engineers,  and  Students. 

oblong  4to,  boards,  i  oo 


24       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Reinhardt,  C.  W.   The  Technic  of  Mechanical  Drafting, 

oblong,  4to,  boards,  *i  oo 
Reiser,  F.     Hardening  and  Tempering  of  Steel.     Trans,  by  A.  Morris  and 

H.   Robson    i2mo,  *3  oo 

Reiser,  N.     Faults  in  the  Manufacture  of  Woolen  Goods.     Trans,  by  A. 

Morris  and  H.  Robson 8vo,  *3  oo 

—  Spinning  and  Weaving  Calculations 8vo,  *6  25 

Renwick,  W.  G.     Marble  and  Marble  Working 8vo,  5  oo 

Reuleaux,  F.     The  Constructor.     Trans,  by  H.  H.  Suplee 4to,  *4  oo 

Reuterdahl,  A.    Theory  and  Design  of  Reinforced  Concrete  Arches. 8vo,  *2  oo 

Rey,  Jean.     The  Range  of  Electric  Searchlight  Projectors 8vo,  *A  50 

Reynolds,   0.,   and  Idell,   F.   E.     Triple   Expansion   Engines.     (Science 

Series  No.  99.)         i6mo,  o  50 

Rhead,  G.  F.     Simple  Structural  Woodwork i2mo,  *i  25 

Rhodes,  H.  J.     Art  of  Lithography 8vo,  6  50 

Rice,  J.  M.,  and  Johnson,  W.  W.     A  New  Method  of  Obtaining  the  Differ- 
ential of  Functions i2mo,  o  50 

Richards,  W.  A.     Forging  of  Iron  and  Steel i2mo,  i  50 

Richards,  W.  A.,  and  North,  H.  B.    Manual  of  Cement  Testing. . .  .  i2mo,  *i  50 

Richardson,  J.     The  Modern  Steam  Engine 8vo,  *3  50 

Richardson,  S.  S.     Magnetism  and  Electricity i2mo,  *2  oo 

Rideal,  S.    Glue  and  Glue  Testing 8vo,  *6  50 

Riesenberg,  F.    The  Men  on  Deck i2tno,  3  oo 

—  Standard  Seamanship  for  the  Merchant  Marine.  i2mo  (In  Press.) 

Rimmer,  E.  J.    Boiler  Explosions,  Collapses  and  Mishaps 8vo,  *i  75 

Rings,  F.     Reinforced  Concrete  in  Theory  and  Practice i2mo,  *4  50 

Reinforced  Concrete  Bridges 4to,  *5  oo 

Ripper,  W.     Course  of  Instruction  in  Machine  Drawing folio,  *6  oo 

Roberts,  F.  C.     Figure  of  the  Earth.     (Science  Series  No.  79.) i6mo,  o  50 

Roberts,  J.,  Jr.     Laboratory  Work  in  Electrical  Engineering 8vo,  *2  oo 

Robertson,  L.  S.     Water-tube  Boilers 8vo,  2  oo 

Robinson,  J.  B.     Architectural  Composition 8vo,  *2  50 

Robinson,  S.  W.     Practical  Treatise  on  the  Teeth  of  Wheels.     (Science 

Series  No.  24.) i6mo,  o  SG 

— • —  Railroad  Economics.     (Science  Series  No.  59.) i6mo,  o  50 

— —  Wrought  Iron  Bridge  Members.     (Science  Series  No.  60.) i6mo,  o  50 

Robson,  J.  H.     Machine  Drawing  and  Sketching 8vo,  *2  oo 

Roebling,  J.  A.    Long  and  Short  Span  Railway  Bridges folio.  25  oo 

Rogers,  A.     A  Laboratory  Guide  of  Industrial  Chemistry 8vo,  2  oo 

• Elements    of    Industrial    Chemistry i2mo,  *3  oo 

—  Manual  of  Industrial  Chemistry 8vo,  *s  oo 

Rogers,  F.     Magnetism  of  Iron  Vessels.     (Science  Series  No.  30.) .  i6mo,  o  So 
Rohland,  P.     Colloidal  and  Crystalloidal  State  of  Matter.     Trans,  by 

W.  J.  Britland  and  H.  E.  Potts i2mo,  *i  25 

Rollinson,  C.     Alphabets Oblong,  i2mo,  *i  oo 

Rose,  J.     The  Pattern-makers'  Assistant 8vo,  2  50 

> — • —  Key  to  Engines  and  Engine-running i2mo,  2  50 

Rose,  T.  K.     The  Precious  Metals.     (Westminster  Series.) 8vo,  *2  oo 

Rosenhain,  W.     Glass  Manufacture.     (Westminster  Series.) 8vo,  *2  oo 

—  Physical  Metallurgy,  An  Introduction  to.      (Metallurgy  Series.) 

8vo,  *3  50 

Roth,   W.    A.     Physical   Chemistry 8vo,  *2  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  25 

Rowan,  F.  J.    Practical  Physics  of  the  Modern  Steam-boiler 8vo,  *3  oo 

and   Idell,   F.   E.     Boiler   Incrustation   and   Corrosion.      (Science 

Series  No.  27.) i6mo,  o  50 

Roxburgh,  W.    General  Foundry  Practice.     (Westminster  Series.)  .8vo,  *2  oo 

Ruhmer,  E.    Wireless  Telephony.     Trans,  by  J.  Erskine-Murray .  .8vo,  *4  50 

Russell,  A.    Theory  of  Electric  Cables  and  Networks 8vo,  *3  oo 

Rust,  A.     Practical  Tables  for  Navigators  and  Aviators 8vo,  3  50 

Rutley,  F.     Elements  of  Mineralogy i2mo,  *i  25 

Sandeman,  E.  A.    Notes  on  the  Manufacture  of  Earthenware.  .  .i2mo,  3  50 

Sanford,  P.  G.     Nitro-explosives 8vo,  *4  oo 

Saunders,  C.  H.     Handbook  of  Practical  Mechanics i6mo,  i  oo 

leather,  i  25 

Sayers,  H.  M.    Brakes  for  Tram  Cars 8vo,  *i  25 

Scheele,  C.  W.     Chemical  Essays 8vo,  *2  oo 

Scheithauer,  W.     Shale  Oils  and  Tars 8vo,  *s  oo 

Scherer,  R.     Casein.     Trans,  by  C.  Salter 8vo,  *4  25 

Schidrowitz,  P.    Rubber,  Its  Production  and  Industrial  Uses Svo,  *6  oo 

Schindler,  K.     Iron  and  Steel  Construction  Works i2mo,  *2  25 

Schmall,  C.  N.    First  Course  in  Analytic  Geometry,  Plane  and  Solid. 

i2mo,  half  leather,  *i  75 

Schmeer,  L.    Flow  of  Water Svo,  *s  oo 

Schumann,  F.    A  Manual  of  Heating  and  Ventilation. ..  .i2mo,  leather,  i  50 

Schwarz,  E.  H.  L.     Causal  Geology Svo,  *3  oo 

Schweizer,  V.     Distillation  of  Resins Svo,  4  50 

Scott,   W.   W.     Qualitative   Analysis.     A  Laboratory  Manual.     New 

Edition 2  50 

Standard   Methods   of   Chemical   Analysis Svo,  *6  oo 

Scribner,  J.  M.    Engineers'  and  Mechanics'  Companion.  .i6mo,  leather,  i  50 
Scudder,    H.     Electrical    Conductivity    and    lonization    Constants    of 

Organic  Compounds Svo,  *3  oo 

Seamanship,  Lectures  on i2mo   (In   Press.) 

Searle,   A.    B.     Modern   Brickmaking Svo,  *7  25 

Cement,  Concrete  and  Bricks Svo,  *6  50 

Searle,    G.    M.      "Sumners'    Method."      Condensed    and    Improved. 

(Science  Series  No.   124.) i6mo,  o  50 

Seaton,  A.  E.     Manual  of  Marine  Engineering Svo  8  oo 

Seaton,  A.  E.,  and  Rounthwaite,  H.  M.    Pocket-book  of  Marine  Engi- 
neering  i6mo,  leather,  5  oo 

Seeligmann,  T.,  Torrilhon,  G.  L.,  and  Falconnet,  H.    India  Rubber  and 

Gutta  Percha.     Trans,  by  J.  G.  Mclntosh Svo,  *s  oo 

Seidell,  A.     Solubilities  of  Inorganic  and  Organic  Substances. ..  .Svo,  3  oo 

Seligman,   R.     Aluminum.      (Metallurgy   Series.) (In  Press.) 

Sellew,  W.  H.     Steel   Rails 4to,  *io  oo 

Railway   Maintenance   Engineering i2mo,  *2  50 

Senter,  G.     Outlines  of  Physical  Chemistry i2mo,  *2  oo 

Text-book  of  Inorganic  Chemistry i2mo,  *3  oo 

Sever,  G.  F.    Electric  Engineering  Experiments Svo,  boards,  *i  oo 

Sever,  G.  F.,  and  Townsend,  F.    Laboratory  and  Factory  Tests  in  Elec- 
trical Engineering Svo,  *2  50 

Sewall,-C.  H.    Wireless  Telegraphy Svo,  *2  oo 

Lessons  in  Telegraphy , i2mo,  *i  oo 


26       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Sewell,  T.     The  Construction  of  Dynamos 8vo,  *3  oo 

Sexton,  A.  H.    Fuel  and  Refractory  Materials tamo,  *z  50 

Chemistry  of  the  Materials  of  Engineering i2mo,  *2  50 

—  Alloys  (Non-Ferrous) 8vo,  *3  oo 

Sexton,  A.  H.,  and  Primrose,  J.  S.  G.  The  Metallurgy  of  Iron  and  Steel. 

8vo,  *6  50 

Seymour,  A.     Modern  Printing  Inks 8vo,  *s  oo 

Shaw,  Henry  S.  H.    Mechanical  Integrators.    (Science  Series  No.  83.) 

i6mo,  o  50 

Shaw,  S.    History  of  the  Staffordshire  Potteries 8vo,  3  oo 

—  Chemistry  of  Compounds  Used  in  Porcelain  Manuf acture . . .  .  8vo,  *6  oo 

Shaw,    T.  R.     Driving  of  Machine  Tools i2mo,  *2  50 

Precision    Grinding    Machines i2mo,  4  50 

Shaw,  W.  N.     Forecasting  Weather 8vo,  *3  50 

Sheldon,  S.,  and  Hausmann,  E.    Direct  Current  Machines izmo,  *2  50 

Alternating  Current  Machines i2mo,  *2  50 

Sheldon,  S.,  and  Hausmann,  E.     Electric  Traction  and  Transmission 

Engineering i2mo,  *2  50 

Physical  Laboratory  Experiments,  for  Engineering  Students.  .8vo,  *i  25 

Shields,  J.  E.     Notes  on  Engineering  Construction i2mo,  i  50 

Shreve,  S.  H.     Strength  of  Bridges  and  Roofs 8vo,  3  50 

Shunk,  W.  F.    The  Field  Engineer i2mo,  fabrikoid,  2  50 

Simmons,  W.  H.,  and  Appleton,  H.  A.    Handbook  of  Soap  Manufacture, 

8vo,  *5  oo 

Simmons,  W.  H.,  and  Mitchell,  C.  A.     Edible  Fats  and  Oils 8vo,  *4  50 

Simpson,  G.    The  Naval  Constructor i2mo,  fabrikoid,  *5  oo 

Simpson;  W.    Foundations. 8vo.   (In  Press.) 

Sinclair,  A.     Development  of  the  Locomotive  Engine. .  .  8vo,  half  leather,  5  oo 

Sindall,  R.  W.    Manufacture  of  Paper.     (Westminster  Series.).  ..  .8vo,  *2  oo 

Sindall,  R.  W.,  and  Bacon,  W.  N.     The  Testing  of  Wood  Pulp 8yo,  *2  50 

Sloane,  T.  O'C.     Elementary  Electrical  Calculations i2mo,  *2  oo 

Smallwood,  J.  C.     Mechanical  Laboratory  Methods.     (Van  Nostrand's 

Textbooks.)    i2mo,  fabrikoid,  *3  oo 

Smith,  C.  A.  M.     Handbook  of  Testing,  MATERIALS 8vo,  *2  50 

Smith,  C.  A.  M.,  and  Warren,  A.  G.     New  Steam  Tables 8vo,  *i  25 

Smith,  C.  F.     Practical  Alternating  Currents  and  Testing 8vo,  *3  50 

Practical    Testing    of    Dynamos    and    Motors 8vo,  *3  oo 

Smith,  F.  A.     Railway  Curves i2mo,  *i  oo 

Standard   Turnouts   on  American   Railroads i2mo,  *i  oo 

Maintenance   of   Way   Standards i2mo,  *i  50 

Smith,  F.  E.     Handbook  of  General  Instruction  for  Mechanics .  .  .  i2mo,  i  50 
Smith,  G.  C.     Trinitrotoluenes  and  Mono-  and  Dinitrotoluenes,  Their 

Manufacture  and   Properties i2mo,  2  oo 

Smith,  H.  G.    Minerals  and  the  Microscope i2mo,  *i  25 

Smith,  J.  C.     Manufacture  of  Paint 8vo,  *3  50 

Smith,  R.  H.     Principles  of  Machine  Work i2mo, 

Advanced  Machine  Work i2mo,  *3  oo 

Smith,  W.     Chemistry  of  Hat  Manufacturing i2mo,  *4  50 

Snell,    A.    T.     Electric    Motive  Power 8vo,  *4  oo 

Snow,  W.  G.     Pocketbook  of  Steam  Heating  and  Ventilation.    (In  Press.) 
Snow,  W.  G.,  and  Nolan,  T.    Ventilation  of  Buildings.     (Science  Series 

No.  5.) i6mo,  o  50 

Soddy,  F.     Radioactivity 8vo,  *3  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  27 

Solomon,  M.     Electric  Lamps.     (Westminster  Series.) 8vo,  *2  oo 

Somerscales,  A.  N.     Mechanics  for  Marine  Engineers i2mo,  *2  oo 

—  Mechanical  and  Marine  Engineering  Science 8vo,  *s  oo 

Sothern,  J.  W.     The  Marine  Steam  Turbine 8vo,  *is  oo 

Verbal  Notes  and  Sketches  for  Marine  Engineers 8vo,  *g  oo 

Sothern,   J.   W.,   and   Sothern,   R.   M.     Elementary  Mathematics   for 

Marine    Engineers i2mo,  *i  50 

—  Simple  Problems  in  Marine  Engineering  Design xarno, 

Southcombe,  J.  E.     Chemistry  of  the  Oil  Industries.     (Outlines  of  In- 
dustrial Chemistry.) 8vo,  *3  oo 

Soxhlet,  D.  H.     Dyeing  and  Staining  Marble.     Trans,  by  A.  Morris  and 

H.  Robson  8vo,  *s  oo 

Spangenburg,  L.  Fatigue  of  Metals.  Translated  by  S.  H.  Shreve. 

(Science  Series  No.  23.) i6mo,  o  50 

Specht,  G.  J.,  Hardy,  A.  S.,  McMaster,  J.  B.,  and  Walling.  Topographical 

Surveying.  (Science  Series  No.  72.) i6mo,  o  50 

Spencer,  A.  S.  Design  of  Steel -Framed  Sheds 8vo,  *3  50 

Speyers,  C.  L.  Text-book  of  Physical  Chemistry 8vo,  *i  50 

Spiegel,  L.  Chemical  Constitution  and  Physiological  Action.  (  Trans. 

by  C.  Luedeking  and  A.  C.  Boylston.) i2mo,  *i  25 

Sprague,  E.  H.  Hydraulics i2mo,  i  50 

—  Elements  of  Graphic  Statics 8vo,  2  50 

—  Stability  of  Masonry i2mo,  i  50 

—  Elementary  Mathematics  for  Engineers i2mo,  *2  50 

—  Stability  of  Arches 121110,  i  50 

—  Strength  of  Structural  Elements i2mo,  2  oo 

Stahl,  A.  W.     Transmission  of  Power.     (Science  Series  No.  28.)  .  i6mo, 

Stahl,  A.  W.,  and  Woods,  A.  T.     Elementary  Mechanism i2mo,  *2  oo 

Staley,  C.,  and  Pierson,  G.  S.     The  Separate  System  of  Sewerage..  .8vo,  *3  oo 

Standage,    H.    C.     Leatherworkers'    Manual 8vo,  *4  50 

—  Sealing  Waxes,  Wafers,  and   Other  Adhesives 8vo,  *2  50 

—  Agglutinants   of    all   Kinds   for   all   Purposes i2mo,  *4  50 

Stanley,  H.    Practical  Applied  Physics (In  Press.) 

Stansbie,  J.  H.     Iron  and  Steel.     (Westminster  Series.) 8vo,  *2  oo 

Steadman,  F.   M.     Unit  Photography. i2mo,  *2  oo 

Stecher,  G.  E.     Cork.    Its  Origin  and  Industrial  Uses i2mo,  i  oo 

Steinheil,  A.,   and   Voit,   E.     Applied   Optics 8vo,  500 

Steinman,  D.  B.     Suspension  Bridges  and  Cantilevers.     (Science  Series 

No.  127.) o  50 

—  Melan's   Steel  Arches  and   Suspension  Bridges 8vo,  *3  oo 

Stevens,  E.  J.     Field  Telephones  and  Telegraphs i  20 

Stevens,  H.  P.     Paper  Mill  Chemist  iomo,  *4  25 

Stevens,  J.  S.     Theory  of  Measurements i2mo,  *i  25 

Stevenson,  J.  L.    Blast-Furnace  Calculations i2mo,  leather,  *2  oo 

Stewart,  G.    Modern  Steam  Traps i2mo,  *i  75 

Stiles,  A.     Tables  for  Field  Engineers i2mo,  i  oo 

Stodola,  A.    Steam  Turbines.    Trans,  by  L.  C.  Loewenstein 8vo,  *s  oo 

Stone,  H.     The  Timbers  of  Commerce 8vo,  3  50 

Stopes,  M.     Ancient  Plants 8vo,  *2  oo 

-  The  Study  of  Plant  Life 8vo,  *2  oo 

Sudborough,  J.  J.,  and  James,  T.  C.    Practical  Organic  Chemistry..  i2mo,  *2  oo 

Suf fling,  E.  R.     Treatise  on  the  Art  of  Glass  Painting 8vo,  *4  25 

Sullivan.  T.  V.,  and  Underwood,  N.    Testing  and  Valuation  of  Build- 
ing and  Engineering  Materials (In  Press.) 


28       D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Sur,  F.  J.  S.     Oil  Prospecting  and  Extracting 8vo,  *i  oo 

Svenson,  C.  L.     Handbook  on  Piping 8vo,  4  oo 

Essentials  of  Drafting 8vo,  i  50 

Swan,  K.     Patents,  Designs  and  Trade  Marks.     (Westminster  Series.). 

8vo,  *2  oo 
Swinburne,  J.,  Wordingham,  C.  H.,  and  Martin,  T.  C.     Electric  Currents. 

(Science  Series  No.  109.) i6mo,  o  50 

Swoope,  C.  W.     Lessons  in  Practical  Electricity i2mo,  *2  oo 

Tailfer,  L.     Bleaching  Linen  and  Cotton  Yarn  and  Fabrics &yo,  8  50 

Tate,  J.  S.     Surcharged  and  Different  Forms  of  Retaining-walls.    (Science 

Series  No.  7.) i6mo,  o  50 

Taylor,  F.  N.     Small  Water  Supplies lamo,  *2  50 

—  Masonry  in  Civil   Engineering 8vo,  *2  50 

Taylor,  T.  U.     Surveyor's  Handbook i2mo,  leather,  *2  oo 

Backbone  of  Perspective i2mo,  *i  oo 

Taylor,   W.   P.     Practical   Cement   Testing 8vo,  *3  oo 

Templeton,  W.    Practical  Mechanic's  Workshop  Companion. 

i2mo,  morocco,  2  oo 
Tenney,    E.    H.      Test    Methods    for    Steam    Power    Plants.      (Van 

Nostrand's  Textbooks.)    i2mo,  *2  50 

Terry,  H.  L.    India  Rubber  and  its  Manufacture.     (Westminster  Series.) 

8vo,  *2  oo 
Thayer,  H.  R.    Structural  Design.    8vo. 

Vol.     I.    Elements  of  Structural  Design *2  oo 

Vol.   II.    Design  of  Simple  Structures *4  oo 

Vol.  HI.    Design  of  Advanced  Structures (In  Preparation.) 

Foundations  and  Masonry (In  Preparation.) 

Thiess,  J.  B.,  and  Joy,  G.  A.    Toll  Telephone  Practice 8vo,  *3  50 

Thorn,  C.,  and  Jones,  W.  H.     Telegraphic  Connections.. .  .oblong,  i2mo,  150 

Thomas,  C.  W.    Paper-makers'  Handbook (In  Press.) 

Thomas,  J.  B.     Strength  of  Ships 8vo,  3  oo 

Thomas,  Robt.  G.     Applied  Calculus i2mo   (In  Press.) 

Thompson,  A.  B.     Oil  Fields  of  Russia 4to,  *7  50 

—  Oil  Field  Development 7  50 

Thompson,  S.  P.    Dynamo  Electric  Machines.     (Science  Series  No.  75.) 

i6mo,  o  So 

Thompson,  W.  P.    Handbook  of  Patent  Law  of  All  Countries i6mo,  i  50 

Thomson,  G.    Modern  Sanitary  Engineering 121110,  *s  oo 

Thomson,  G.  S.     Milk  and  Cream  Testing i2mo,  *2  25 

—  Modern  Sanitary  Engineering,  House  Drainage,  etc . 8vo,  *3  oo 

Thornley,  T.     Cotton  Combing  Machines 8vo,  *3  oo 

—  Cotton  Waste    8vo,  *4  50 

Cotton  Spinning.     8vo. 

First  Year   *2  oo 

Second  Year  *4  25 

Third  Year  *3  50 

Thurso,  J.  W.     Modern  Turbine  Practice 8vo,  *4  oo 

Tidy,  C.  Meymott.     Treatment  of  Sewage.     (Science  Series  No.  94.)  i6mo,  o  50 
Tillmans,   J.    Water   Purification   and   Sewage   Disposal.    Trans,    by 

Hugh  S.  Taylor 8vo,  *2  oo 

Tinney,  W.  H.     Gold-mining  Machinery 8vo,  *3  oo 

Titherley,  A.  W.    Laboratory  Course  of  Organic  Chemistry 8vo,  *2  oo 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  29 

Tizard,  H.  T.    Indicators „ (/„  Press.') 

Toch,  M.     Chemistry  and  Technology  of  Paints 8vo,  *4  oo 

-  Materials  for  Permanent  Painting I2mo,  *2  oo 

Tod,   J.,   and   McGibbon,   W.   C.     Marine    Engineers'    Board   of   Trade 

Examinations    8vo,  *2  oo 

Todd,  J.,  and  Whall,  W.  B.     Practical  Seamanship 8vo,  8  oo 

Tonge,  J.     Coal.     (Westminster  Series.) 8vo,  *2  oo 

Townsend,  F.     Alternating  Current  Engineering 8vo,  boards,  *o  75 

Townsend,  J.  S.     lonization  of  Gases  by  Collision 8vo,  *i  25 

Transactions  of  the  American  Institute  of  Chemical  Engineers,     8vo. 

Vol.  I.  to  X.,  1908-1917 8vo,  each,  6  oo 

Traverse  Tables.     (Science  Series  No.  115.) i6mo,  o  50 

morocco,  i  oo 

Treiber,  E.    Foundry  Machinery.    Trans,  by  C.  Salter i2mo,  i  50 

Trinks,  W.,  and  Housum,  C.     Shaft  Governors.     (Science  Series  No.  122.) 

i6mo,  o  50 

Trowbridge,  W.  P.     Turbine  Wheels.     (Science  Series  No.  44.) . .  i6mo,  o  50 

Tucker,  J.  H.     A  Manual  of  Sugar  Analysis 8vo,  3  50 

Tunner,  P.  A.     Treatise  on  Roll-turning.     Trans,  by  J.  B.  Pearse. 

8vo,  text  and  folio  atlas,  10  oo 
Turnbull,  Jr.,  J.,  and  Robinson,  S.  W.     A  Treatise  on  the  Compound 

Steam-engine.     (Science  Series  No.  8.) i6mo, 

Turner,  H.     Worsted  Spinners'  Handbook i2mo,  *3  50 

Turrill,  S.  M.     Elementary  Course  in  Perspective i2mo,  *i  25 

Twyford,  H.  B.     Purchasing 8vo,  *3  oo 

—  Storing,  Its  Economic  Aspects  and  Proper  Methods 8vo,  3  50 

Tyrrell,  H.  G.    Design  and  Construction  of  Mill  Buildings 8vo,  *4  oo 

—  Concrete  Bridges  and  Culverts i6mo,  leather,  *s  oo 

Artistic    Bridge   Design 8vo,  *3  oo 

Underbill,  C.  R.     Solenoids,  Electromagnets  and  Electromagnetic  Wind- 
ings  I2H10,  *2  OO 

Underwood,  N.,  and  Sullivan,  T.  V.     Chemistry  and   Technology  of 

Printing   Inks    8vo,  *3  oo 

Urquhart,  J.  W.    Electro-plating i2mo,  2  oo 

Electrotyping i2mo,  2  oo 

Usborne,  P.  O.  G.     Design  of  Simple  Steel  Bridges 8vo,  *4  oo 

Vacher,  F.    Food  Inspector's  Handbook  i2mp, 

Van  Nostrand's  Chemical  Annual.     Fourth  issue  igiS.fabrikoid,  i2mo,  *3  oo 

—  Year  Book  of  Mechanical  Engineering  Data (In  Press.) 

Van  Wagenen,  T.  F.     Manual  of  Hydraulic  Mining i6mo,  i  oo 

Vega,  Baron  Von.     Logarithmic  Tables 8vo,  2  50 

Vincent,  C.    Ammonia  and  its  Compounds.    Trans,  by  M.  J.  Salter. 8vo,  *3  oo 

Volk,  C.     Haulage  and  Winding  Appliances .  .8vo,  *4  oo 

Von  Georgievics,  G.     Chemical  Technology  of  Textile  Fibres.     Trans, 
by  C.  Salter 8vo, 

-  Chemistry  of  Dyestuffs.     Trans,  by  C.  Salter 8vo,  *4  50 

Vose,  G.  L.     Graphic  Method  for  Solving  Certain  Questions  in  Arithmetic 

and  Algebra      (Science  Series  No.  16.) i6mo,  o  So 


-o        D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG 

Vosmaer,  A.     Ozone .8vo,  *2  50 

Wabner,  R.     Ventilation  in  Mines.     Trans,  by  C.  Salter 8vo,  *6  50 

Wade,  E.  J.     Secondary  Batteries 8vo,  *4  o° 

Wadmore,  T.  M.     Elementary  Chemical  Theory i2mo,  *i  50 

Wagner,   E.     Preserving   Fruits,   Vegetables,   and   Meat... zarno,  *s  oo 

Wagner,  J.  B.     A  Treatise  on  the  Natural  and  Artificial  Processes  of 

Wood    Seasoning 8vo,  3  oo 

Waldram,  P.  J.     Principles  of  Structural  Mechanics . i2mo,  *3  oo 

Walker,  F.    Dynamo  Building.     (Science  Series  No.  98.) i6mo,  o  50 

Walker,  J.     Organic  Chemistry  for  Students  of  Medicine 8vo,  "3  oo 

Walker,  S.  F.     Steam  Boilers,  Engines  and  Turbines 8vo,  3  oo 

—  Refrigeration,  Heating  and  Ventilation  on  Shipboard i2mo,  *2  oo 

— • —  Electricity  in  Mining , 8vo,  *4  50 

Wallis-Tayler,  A.  J.     Bearings  and  Lubrication 8vo,  *i  50 

—  Aerial   or  Wire   Ropeways 8vo,  *3  oo 

—  Preservation  of  Wood 8vo,  4  oo 

—  Refrigeration,  Cold  Storage  and  Ice  Making 8vo,  5  50 

—  Sugar  Machinery zamo,  *a  50 

Walsh,  J.  J.    Chemistry  and  Physics  of  Mining  and  Mine  Ventilation, 

i2mo,  *2  oo 

Wanklyn,  J.  A.    Water  Analysis i2mo,  2  oo 

Wansbrough,  W.  D.    The  A  B  C  of  the  Differential  Calculus i2mo,  *2  50 

—  Slide  Valves i2mo,  *2  oo 

Waring,  Jr.,  G.  E.    Sanitary  Conditions.    (Science  Series  No.  31.)  .  i6mo,  o  50 

—  Sewerage  and  Land  Drainage *6  oo 

— •  Modern  Methods  of  Sewage  Disposal i2mo,  2  oo 

—  How  to  Drain  a  House i2mo,  i  25 

Warnes,  A.  R.     Coal  Tar  Distillation 8vo,  *s  oo 

Warren,  F.  D.    Handbook  on  Reinforced  Concrete. i2mo,  *2  50 

Watkins,  A.     Photography.     (Westminster  Series.) 8vo,  *2  oo 

Watson,  E.  P.    Small  Engines  and  Boilers i2mo,  i  25 

Watt,  A.     Electro-plating  and  Electro-refining  of  Metals 8vo,  *4  50 

•  Electro -metallurgy 121110,  i  oo 

The  Art  of  Soap  Making 8vo,  3  oo 

Leather  Manufacture 8vo,  *4  oo 

Paper-Making 8vo,  3  oo 

Webb,  H.  L.  Guide  to  the  Testing  of  Insulated  Wires  and  Cables.  i2mo,  i  oo 

Webber,  W.  H.  Y.    Town  Gas.     (Westminster  Series.) 8vo,  *2  oo 

Wegmann,    Edward.      Conveyance    and    Distribution    of    Water    for 

Water  Supply 8vo,  5  oo 

Weisbach,  J.    A  Manual  of  Theoretical  Mechanics 8vo,  *6  oo 

sheep,  *7  50 

Weisbach,  J.,  and  Herrmann,  G.     Mechanics  of  Air  Machinery ....  8  vo,  *3  75 

Wells,  M.   B.     Steel  Bridge  Designing 8vo,  *2  50 

Wells,  Robt.     Ornamental   Confectionery i2mo,  3  oo 

Weston,  E.  B.    Loss  of  Head  Due  to  Friction  of  Water  in  Pipes.  .i2mo,  *i  50 

Wheatley,  0.     Ornamental  Cement  Work 8vo,  *2  25 

Whipple,  S.    An  Elementary  and  Practical  Treatise  on  Bridge  Building. 

8vo,  3  oo 
White,  C.  H.     Methods  of  Metallurgical  Analysis.     (Van  Nostrand's 

Textbooks.)     i2mo,  2  50 


D.  VAN  NOSTRAND  CO.'S  SHORT  TITLE  CATALOG  31 

White,  G.  F.    Qualitative  Chemical  Analysis i2mo,  *i  25 

White,  G.  T.     Tootned  Gearing i2mo,  *2  25 

White,  H.  J.     Oil  lank  bceaiuers 12010,  i  50 

Whitelaw,   John.     Surveying 8vo,  4  50 

Widmer,  E.  J.     Military   Balloons 8vo,  3  oo 

Wilcox,  R.  M.      Cantilever  Bridges.     (Science  Series  No.  25.) . ..  .i6mo,  o  50 

Wilda,  H.    Steam  Turbines.     Trans,  by  C.  Salter i2mo,  2  50 

—  Cranes  and  Hoists.     Trans,   by   C.  Salter i2mo,  2  50 

Wilkinson,  H.  D.     Submarine  Cable  Laying  and  Repairing 8vc,  *6  oo 

Williamson,   J.     Surveying 8vo,  *s  oo 

Williamson,  R.  S.     On  the  Use  of  the  Barometer 4to,  15  oo 

—  Practical  Tables  in  Meteorology  and  Hypsometery 4to,  2  50 

Wilson,  F.  J.,  and  Heilbron,  I.  M.    Chemical  Theory  and  Calculations. 

i2mo,  *i  25 

Wilson,  J.  F.     Essentials  of  Electrical  Engineering 8vo,  2  50 

Wimperis,  H.  E.     Internal  Combustion  Engine 8vo,  ^3  oo 

—  Application  of  Power  to  Road  Transport i2mo,  *i  50 

—  Primer  of  Internal  Combustion  Engine i2mo,  *i  oo 

Winchell,  N.  H.,  and  A.  N.    Elements  of  Optical  Mineralogy 8vo,  *3  50 

Winslow,  A.    Stadia  Surveying.     (Science  Series  No.  77.) i6mo,  o  50 

Wisser,  Lieut.  J.  P.     Explosive  Materials.     (Science  Series  No.  70.) 

i6mo,  o  50 

Wisser,  Lieut.  J.  P.  Modern  Gun  Cotton.  (Science  Series  No.  89.)  .i6mo,  o  50 

Wolff,  C.  E.  Modern  Locomotive  Practice 8vo,  *4  20 

Wood,  De  V.  Luminiferous  Aether.  (Science  Series  No.  85). . .  i6mo,  o  50 
Wood,  J.  K.  Chemistry  of  Dyeing.  (Chemical  Monographs  No.  2.) 

i2mo,  *i  oo 

Worden,  E.  C.  The  Nitrocellulose  Industry.  Two  Volumes 8vo,  *io  oo 

—  Technology  of  Cellulose  Esters.     In  10  volumes.    8vo. 

Vol.  VIII.     Cellulose  Acetate *5  oo 

Wren,  H.    Organometallic  Compounds  of  Zinc  and  Magnesium.    (Chem- 
ical   Monographs    No.    i.) i2ino,  *i  oo 

Wright,  A.  C.     Analysis  of  Oils  and  Allied  Substances 8vo,  *3  50 

Simple  Method  for  Testing  Painters'  Materials 8vo,  *3  oo 


Wright,  H.  E.     Handy  Book  for  Brewers 8vo,  *6  oo 

Wright,  J.     Testing,  Fault  Finding,  etc.,  for  Wiremen.     (Installation 

Manuals  Series.) 161110,  *o  50 

Wright,  T.  W.     Elements  of  Mechanics 8vo,  *2  50 

Wright,  T.  W.,  and  Hayf ord,  J.  F.    Adjustment  of  Observations .  . .  8vo,  *3  oo 
Wynne,  W.  E.,  and  Sparagen,  W.     Handbook  of  Engineering  Mathe- 
matics     8vo,  *2  oo 

Yoder,  J.  H.,  and  Wharen,  G.  B.    Locomotive  Valves  and  Valve  Gears, 

8vo,  *3  oo 

Young,  J.  E.    Electrical  Testing  for  Telegraph  Engineers 8vo,  *4  oo 

Young,  R.   B.     The  Banket . 8vo,  3  50 

Youngson.     Slide  Valve  and  Valve  Gears 8vo,  3  oo 

Zahner,  R.    Transmission  of  Power.     (Science  Series  No.  40.)..i6mo, 

Zeidler,  J.,  and  Lustgarten,  J.     Electric  Arc  Lamps 8vo,  *2  oo 

Zeuner,  A.    Technical  Thermodynamics.    Trans,  by  J.  F.  Klein.    Two 

Volumes 8vo,  *8  oo 

Zimmer,  G.  F.    Mechanical  Handling  and  Storing  of  Materials. ..  -4to,  *i2  50 
—  Mechanical   Handling  of   Material   and   Its  National  Importance 

During  and  After  the  War : .  . .  -4to,  4  oo 

Zipser,  J.    Textile  Raw  Materials.    Trans,  by  C.  Salter 8vo,  *6  25 

Zur  Nedden,  F.    Engineering  Workshop  Machines  and  Processes.  Trans. 

by  J.  A.  Davenport 8vo,  *2  oo 


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